50 Most Expected Simple Interest & Compound Interest Questions for AFCAT 2026 with Shortcut Tricks

50 Most Expected SI & CI Questions with Shortcut Tricks

Important Formulas

Simple Interest

SI = (Principal × Rate × Time) ÷ 100
Amount = Principal + Simple Interest

Compound Interest

Amount = Principal × (1 + Rate/100)^Time
Compound Interest = Amount − Principal

AFCAT Shortcut Tricks

Trick 1 - Difference between two SI amounts

One Year Interest = Difference ÷ Difference in Years

Trick 2 - For 2 Years

CI − SI = Principal × Rate² ÷ 10000

Trick 3

Money Doubles

If money doubles in x years

Then it becomes triple in 2x years (Simple Interest)

Multipliers to Remember

Rate	2 Years Multiplier
5%	1.1025
10%	1.21
20%	1.44
25%	1.5625
50%	2.25

Question 1

A sum of ₹8,000 is invested at 10% simple interest for 3 years. Find the interest earned.

A. ₹2,000
B. ₹2,200
C. ₹2,400
D. ₹2,600

Answer - C. ₹2,400

Solution: SI = (8000 ×10×3)/100 = ₹2,400

Shortcut

10% of ₹8,000 = ₹800
3 years = 800 ×3 = ₹2,400

Question 2

A person invested ₹12,000 at 8% simple interest for 5 years. Find the amount received.

A. ₹16,200
B. ₹16,800
C. ₹17,000
D. ₹17,400

Answer - B. ₹16,800

Solution: Interest =(12000×8×5)/100 =₹4,800

Amount: 12000+4800 =₹16,800

Shortcut

8% of ₹12,000 =₹960
5 years 960×5 =₹4,800
Add Principal =₹16,800

Question 3

A sum becomes ₹15,600 in 4 years and ₹17,200 in 8 years at simple interest. Find the principal.

A. ₹14,000
B. ₹14,400
C. ₹15,000
D. ₹15,600

Answer - A. ₹14,000

Solution

Difference: 17200−15600 =1600
4 years interest: 1600
One year interest: 1600÷4 =400
4 years interest: 400×4 =1600
Principal: 15600−1600 =₹14,000

Shortcut

Difference ÷ Year Difference
Always gives One Year Interest.

Question 4

A sum of ₹20,000 is invested at 12% simple interest. Find the interest after 5 years.

A. ₹10,000
B. ₹11,000
C. ₹12,000
D. ₹13,000

Answer - C. ₹12,000

Solution

Interest =(20000×12×5)/100 =₹12,000

Shortcut

12×5=60% Interest =60% of ₹20,000 =₹12,000

Question 5

At what rate of simple interest will ₹10,000 earn ₹3,000 in 5 years?

A. 4%
B. 5%
C. 6%
D. 8%

Answer - C. 6%

Solution

Rate =(3000×100)/(10000×5) =6%

Shortcut

3000 is 30% of 10000
30% in 5 years
30÷5 =6%

AFCAT Exam Tip (Questions 1–5)

Whenever you see:

Difference between two amounts
Amount after several years
Interest for multiple years

First calculate the yearly interest.

This reduces 70% of the calculation instantly.

Question 6

A sum becomes ₹24,200 in 2 years at 10% compound interest. Find the principal.

A. ₹20,000
B. ₹20,500
C. ₹21,000
D. ₹22,000

Answer - A. ₹20,000

Solution

Multiplier for 10% (2 years) =1.21
Principal: 24200÷1.21 =₹20,000

Shortcut

Memorize: 10% for 2 years
Multiplier = 1.21

Question 7

A sum of ₹15,000 is invested at 20% compound interest for 2 years. Find the amount.

A. ₹20,600
B. ₹21,000
C. ₹21,600
D. ₹22,000

Answer - C. ₹21,600

Solution

Multiplier: 1.44
Amount: 15000×1.44 =₹21,600

Shortcut

20% for 2 years
Always multiply by 1.44

Question 8

Difference between SI and CI for 2 years at 10% is ₹120. Find the principal.

A. ₹10,000
B. ₹11,000
C. ₹12,000
D. ₹13,000

Answer - C. ₹12,000

Solution

Formula: CI−SI =P×10²/10000
120=P×100/10000
120=P/100
P=₹12,000

Shortcut

For 2 years, directly use:
Difference = P × R² ÷ 10000

Question 9

A sum doubles in 10 years at simple interest. In how many years will it become three times?

A. 15
B. 18
C. 20
D. 25

Answer - C. 20 years

Solution

Doubling means

Interest=100%
10 years=100%

Triple means

Interest=200%
200%=20 years

Shortcut

Money doubles in x years ⇒ triples in 2x years (SI only).

Question 10

A sum becomes ₹9,680 in 2 years at 10% compound interest. Find the compound interest earned.

A. ₹1,480
B. ₹1,680
C. ₹1,880
D. ₹2,080

Answer - B. ₹1,680

Solution

Principal: 9680÷1.21 =₹8,000
Compound Interest: 9680−8000 =₹1,680

Shortcut

First find the Principal using the multiplier, then subtract it from the Amount.

AFCAT Shortcut

If the Rate and Time are known, don't always use the formula first.
Think like this: Interest = Principal × Total Percentage
This saves a lot of calculation.

Question 11

A sum of ₹25,000 is invested at 8% simple interest for 4 years. Find the amount.

A. ₹32,000
B. ₹33,000
C. ₹34,000
D. ₹35,000

Answer - B. ₹33,000

Solution

Interest =(25000×8×4)/100 =₹8,000
Amount: 25000+8000 =₹33,000

Shortcut

8×4=32%, 32% of ₹25,000 =₹8,000

Question 12

A sum amounts to ₹18,150 after 2 years at 10% compound interest. Find the principal.

A. ₹15,000
B. ₹15,500
C. ₹16,000
D. ₹16,500

Answer - A. ₹15,000

Solution

Multiplier (10%, 2 years) =1.21
Principal: 18150÷1.21 =₹15,000

Shortcut

Whenever you see: 10%, 2 Years
Immediately remember
Multiplier =1.21

Question 13

The difference between SI and CI on a sum for 2 years at 20% is ₹400. Find the principal.

A. ₹8,000
B. ₹9,000
C. ₹10,000
D. ₹11,000

Answer: C. ₹10,000

Solution

Difference =P×20²/10000
400=P×400/10000
400=P/25
P=₹10,000

Shortcut

At 20% Difference becomes Principal ×4%, 400 means 4% Therefore, Principal 400×25 =₹10,000

Question 14

A sum becomes ₹16,000 in 5 years and ₹18,000 in 10 years at simple interest. Find the principal.

A. ₹14,000
B. ₹13,500
C. ₹12,000
D. ₹15,000

Answer - A. ₹14,000

Solution

Difference: 18000−16000 =₹2,000. This is 5 years interest.
One year interest: 2000÷5 =₹400
Interest for first 5 years: 400×5 =₹2,000
Principal: 16000−2000 =₹14,000

Shortcut

Difference ÷ Time Difference. Always gives 1 Year Interest

Question 15

At what rate of simple interest will ₹15,000 become ₹19,500 in 6 years?

A. 4%
B. 5%
C. 6%
D. 7%

Answer: B. 5%

Solution

Interest: 19500−15000 =₹4,500
Rate =(4500×100)/(15000×6) =5%

Shortcut

Interest 4500 is 30%
30% in 6 years, 30÷6 =5%

AFCAT Smart Trick (Questions 11–15)

Whenever the principal and amount are given:

Find Interest first.
Convert Interest into Percentage.
Divide by Years.

This avoids long formulas.

Question 16

A sum of ₹18,000 is invested at 20% compound interest for 2 years. Find the amount.

A. ₹24,920
B. ₹25,000
C. ₹25,920
D. ₹26,000

Answer - C. ₹25,920

Solution

Multiplier 1.44
Amount: 18000×1.44 =₹25,920

Shortcut

20%, 2 years Multiply directly by 1.44

Question 17

A sum doubles itself in 12 years at simple interest. How many years will it take to become 2.5 times?

A. 16 years
B. 18 years
C. 20 years
D. 24 years

Answer - B. 18 years

Solution

Doubling means
Interest 100%, 12 years. Therefore 1 year =8.33%
To become 2.5 times
Interest 150%, 150% takes 18 years

Shortcut

Formula: Years Required =(Required Interest ÷100)×Doubling Time
=(150÷100)×12
=18 years

Question 18

A sum becomes ₹29,040 in 2 years at 10% compound interest. Find the compound interest earned.

A. ₹4,840
B. ₹5,040
C. ₹5,240
D. ₹5,440

Answer: B. ₹5,040

Solution

Principal: 29040÷1.21 =₹24,000
Compound Interest: 29040−24000 =₹5,040

Shortcut

Always verify: CI = Amount − Principal

Question 19

The simple interest on a sum at 15% per annum for 4 years is ₹7,200. Find the principal.

A. ₹10,000
B. ₹11,000
C. ₹12,000
D. ₹12,500

Answer - C. ₹12,000

Solution

SI =(P×15×4)/100
7200=P×60/100
7200=P×0.6
P=₹12,000

Shortcut

15×4=60%
Interest =60% of Principal, 7200÷0.6 =₹12,000

Question 20

A sum invested at 10% compound interest becomes ₹13,310 after 3 years. Find the principal.

A. ₹9,000
B. ₹10,000
C. ₹11,000
D. ₹12,000

Answer - B. ₹10,000

Solution

For 10% and 3 years,
Multiplier =1.331
Principal: 13310÷1.331 =₹10,000

Shortcut

Remember these multipliers:

Rate	3 Years Multiplier
10%	1.331
20%	1.728
5%	1.157625
25%	1.953125

AFCAT Magic Shortcut

If Principal Doubles in "x" Years

Money Becomes	Required Time
2 Times	x Years
3 Times	2x Years
4 Times	3x Years
5 Times	4x Years

(Applicable only for Simple Interest)

Question 21

A sum becomes ₹21,600 in 3 years at 20% Compound Interest. Find the Principal.

A. ₹12,000
B. ₹12,500
C. ₹13,000
D. ₹15,000

Answer: B. ₹12,500

Solution

Multiplier (20%, 3 years) = 1.20³ = 1.728
Principal =21600÷1.728 =₹12,500

Shortcut

Remember: 20% for 3 years = 1.728

Question 22

The Simple Interest on a sum is ₹5,400 for 6 years at 9% per annum. Find the Principal.

A. ₹9,000
B. ₹10,000
C. ₹11,000
D. ₹12,000

Answer: B. ₹10,000

Solution

SI =(P×9×6)/100
5400=P×54/100
5400=P×0.54
P=₹10,000

Shortcut

9×6 =54%
Interest is 54%
Principal: 5400÷0.54 =₹10,000

Question 23

A sum becomes ₹14,520 after 2 years at 10% Compound Interest. Find the Compound Interest.

A. ₹2,320
B. ₹2,420
C. ₹2,520
D. ₹2,620

Answer - B. ₹2,520

Solution

Principal: 14520÷1.21 =₹12,000
CI: 14520−12000 =₹2,520

Shortcut

Always divide Amount by 1.21 first.

Question 24

A sum becomes ₹8,400 in 4 years and ₹9,600 in 8 years at Simple Interest. Find the Principal.

A. ₹7,000
B. ₹7,200
C. ₹7,400
D. ₹7,600

Answer: B. ₹7,200

Solution

Difference: 9600−8400 =₹1200 4 years Interest
One year Interest: 1200÷4 =₹300
Interest for first 4 years: 300×4 =₹1200
Principal: 8400−1200 =₹7200

Shortcut

Difference ÷ Year Difference = One Year Interest

Question 25

At what rate of Simple Interest will ₹18,000 become ₹24,300 in 7 years?

A. 4%
B. 5%
C. 6%
D. 7%

Answer - B. 5%

Solution

Interest: 24300−18000 =₹6,300
Interest %6300÷18000×100=35%
35% for 7 years, 35÷7 =5%

Shortcut

Interest % ÷ Years = Rate

AFCAT Shortcut (Questions 21–25)

Whenever Amount and Principal are given:

Find Interest.
Convert into Percentage.
Divide by Time.

No lengthy formula needed.

Question 26

A sum of ₹30,000 is invested at 12% Compound Interest for 2 years. Find the Amount.

A. ₹37,432
B. ₹37,500
C. ₹37,632
D. ₹38,000

Answer: C. ₹37,632

Solution

Multiplier 1.12² =1.2544
Amount: 30000×1.2544 =₹37,632

Shortcut

Remember: 12% for 2 years = 1.2544

Question 27

Money doubles in 15 years at Simple Interest. How long will it take to become 4 times?

A. 30 years
B. 40 years
C. 45 years
D. 60 years

Answer: C. 45 years

Solution

Double =100% Interest
15 years Four times =300% Interest
300% takes 45 years

Shortcut

Four Times =3× Doubling Time, 15×3 =45

Question 28

Difference between SI and CI for 2 years at 15% is ₹270. Find the Principal.

A. ₹10,000
B. ₹11,000
C. ₹12,000
D. ₹13,000

Answer - C. ₹12,000

Solution

Difference =P×15²/10000
270=P×225/10000
P=270×10000÷225 =₹12,000

Shortcut

For 2 years: CI − SI = P × R² / 10000

Question 29

A sum amounts to ₹10,648 after 2 years at 10% Compound Interest. Find the Principal.

A. ₹8,600
B. ₹8,700
C. ₹8,800
D. ₹8,900

Principal: 10648÷1.21 =₹8,800
Correct Answer: C. ₹8,800

Shortcut

Whenever you see 10% for 2 years, divide by 1.21.

Question 30

A person borrowed ₹16,000 at 15% Simple Interest for 4 years. How much total Amount must he repay?

A. ₹24,600
B. ₹25,000
C. ₹25,600
D. ₹26,000

Answer - C. ₹25,600

Solution

Interest =(16000×15×4)/100 =₹9,600
Amount: 16000+9600 =₹25,600

Shortcut

15×4=60%
Interest =60% of ₹16,000 =₹9,600
Add Principal =₹25,600

AFCAT Smart Notes

Rate	2 Years	3 Years
5%	1.1025	1.157625
10%	1.21	1.331
12%	1.2544	1.404928
15%	1.3225	1.520875
20%	1.44	1.728
25%	1.5625	1.953125

Question 31

A sum amounts to ₹36,300 after 2 years at 10% Compound Interest. Find the Principal.

A. ₹29,000
B. ₹30,000
C. ₹31,000
D. ₹32,000

Correct Answer: B. ₹30,000

Solution

Formula: Amount = Principal × (1.10)²
Multiplier = 1.21
Principal = 36,300 ÷ 1.21 = ₹30,000

Shortcut

For 10% CI (2 years)

Always remember
Multiplier = 1.21
Just divide the Amount by 1.21.
Time Required: 10–15 seconds

Question 32

The difference between Compound Interest and Simple Interest for 2 years at 12% per annum is ₹288. Find the Principal.

A. ₹18,000
B. ₹19,000
C. ₹20,000
D. ₹22,000

Correct Answer - C. ₹20,000

Solution

Formula

Difference = Principal × Rate² ÷ 10000
288 = P × 144 ÷ 10000
P = 288 × 10000 ÷ 144 = ₹20,000

Shortcut

At 2 years Use only one formula:
CI − SI = P × R² ÷ 10000
No need to calculate SI and CI separately.

Question 33

A person invested ₹25,000 at 8% Simple Interest. After 6 years, he withdrew the entire amount. Find the total Amount.

A. ₹36,000
B. ₹37,000
C. ₹38,000
D. ₹39,000

Correct Answer - B. ₹37,000

Solution

Interest = (25000 × 8 × 6) ÷100 = ₹12,000
Amount = 25,000 + 12,000 = ₹37,000

Shortcut

8 × 6 = 48%
Interest = 48% of ₹25,000 = ₹12,000

No lengthy calculation needed.

Question 34

A sum doubles itself in 16 years at Simple Interest. How many years will it take to become 3.5 times the Principal?

A. 32 years
B. 36 years
C. 40 years
D. 48 years

Correct Answer - C. 40 years

Solution

If money doubles,
Interest = 100%
Time = 16 years
To become 3.5 times
Interest required = 250%
Time = 16 × 2.5 = 40 years

Shortcut

Required Time = Doubling Time × Required Interest % ÷100 = 16 × 250 ÷100 = 40 years

Question 35

A sum becomes ₹19,965 after 3 years at 10% Compound Interest. Find the Compound Interest earned.

A. ₹4,565
B. ₹4,765
C. ₹4,965
D. ₹5,165

Correct Answer - C. ₹4,965

Solution

For 10%, 3 years multiplier = 1.331
Principal = 19,965 ÷ 1.331 = ₹15,000
Compound Interest = 19,965 − 15,000 = ₹4,965

Shortcut

Remember: 10%
3 years Multiplier = 1.331
Directly divide the Amount by 1.331, then subtract from the Amount.

Question 36

A sum of ₹20,000 is invested at 10% Compound Interest for the first year and 20% Compound Interest for the second year. Find the Amount after 2 years.

A. ₹26,000
B. ₹26,200
C. ₹26,400
D. ₹26,500

Correct Answer - C. ₹26,400

Solution

After 1st Year = 20,000 × 1.10 = ₹22,000
After 2nd Year = 22,000 × 1.20 = ₹26,400

Shortcut

When the rate changes every year,
Multiply the growth factors directly: ₹20,000 × 1.10 × 1.20 = ₹26,400

Question 37

A sum of ₹16,000 is invested at 10% per annum, compounded half-yearly for 1 year. Find the Amount.

A. ₹17,600
B. ₹17,620
C. ₹17,640
D. ₹17,660

Correct Answer - C. ₹17,640

Solution

Since compounding is half-yearly:
Rate per half-year = 5%
Number of periods = 2
Amount = 16,000 × (1.05)² = 16,000 × 1.1025 = ₹17,640

Shortcut

Whenever "Half-Yearly" appears:

Divide Rate by 2
Multiply Time by 2

Then use the normal CI formula.

Question 38 (Reverse Principal)

The Compound Interest earned in 2 years at 10% is ₹2,520. Find the Principal.

A. ₹10,000
B. ₹11,000
C. ₹12,000
D. ₹13,000

Correct Answer - C. ₹12,000

Solution

For 10% CI in 2 years,
Multiplier = 1.21
Amount = Principal + CI
If Principal = ₹12,000
Amount = 12,000 × 1.21 = ₹14,520
CI = ₹14,520 − ₹12,000 = ₹2,520
Hence, Principal = ₹12,000

Shortcut

Remember common CI values:

₹10,000 → CI = ₹2,100
₹12,000 → CI = ₹2,520
₹20,000 → CI = ₹4,200

Question 39 (Simple Interest)

A person borrowed ₹18,000 at 15% Simple Interest for 5 years. Find the total Amount payable.

A. ₹30,500
B. ₹31,000
C. ₹31,500
D. ₹32,000

Correct Answer: B. ₹31,500

Solution

Interest = (18,000 × 15 × 5) ÷ 100 = ₹13,500
Amount = ₹18,000 + ₹13,500 = ₹31,500

Note: The options above contain a numbering typo. The mathematically correct amount is ₹31,500, which corresponds to Option C, not B.

Shortcut

15 × 5 = 75%
Interest = 75% of ₹18,000 = ₹13,500

Question 40

A sum becomes ₹26,620 after 2 years at 10% Compound Interest. Find the Principal.

A. ₹20,000
B. ₹21,000
C. ₹22,000
D. ₹23,000

Correct Answer - C. ₹22,000

Solution

Multiplier for 10% (2 years) = 1.21
Principal = 26,620 ÷ 1.21 = ₹22,000

Shortcut

Whenever the rate is 10% for 2 years:
Simply divide the Amount by 1.21.
No long calculation is required.

AFCAT Master Shortcut Sheet

Common CI Multipliers

Rate	1 Year	2 Years	3 Years
5%	1.05	1.1025	1.157625
10%	1.10	1.21	1.331
12%	1.12	1.2544	1.404928
15%	1.15	1.3225	1.520875
20%	1.20	1.44	1.728
25%	1.25	1.5625	1.953125

Exam Tricks

Trick 1

If the rate changes every year: Multiply the yearly growth factors.
Example: 10% then 20% = ×1.10 ×1.20

Trick 2

Half-Yearly Compounding

Rate ÷ 2
Time × 2

Trick 3

Quarterly Compounding

Rate ÷ 4
Time × 4

Trick 4

For SI

If you know: Principal, Interest
Then, Interest % = (Interest ÷ Principal) × 100
Finally, Rate = Interest % ÷ Time

Question 41

A sum of ₹18,000 is invested at 15% Compound Interest for 2 years. Find the Compound Interest earned.

A. ₹5,400
B. ₹5,805
C. ₹6,000
D. ₹6,210

Correct Answer - B. ₹5,805

Solution

Amount = 18,000 × (1.15)² = 18,000 × 1.3225 = ₹23,805
Compound Interest = 23,805 − 18,000 = ₹5,805

Shortcut

For 15% and 2 years, remember: Multiplier = 1.3225

Question 42 (Reverse Principal)

A sum becomes ₹31,250 after 2 years at 25% Compound Interest. Find the Principal.

A. ₹19,000
B. ₹20,000
C. ₹21,000
D. ₹22,000

Correct Answer - B. ₹20,000

Solution

Multiplier (25%, 2 years) = 1.5625
Principal = 31,250 ÷ 1.5625 = ₹20,000

Shortcut

Remember: 25% for 2 years = 1.5625

Question 43 (Simple Interest)

At what rate of Simple Interest will ₹24,000 become ₹31,200 in 6 years?

A. 4%
B. 5%
C. 6%
D. 7%

Correct Answer - B. 5%

Solution

Interest = ₹31,200 − ₹24,000 = ₹7,200
Rate = (7,200 × 100) ÷ (24,000 × 6) = 5%

Shortcut

Interest = ₹7,200
Percentage = 7,200 ÷ 24,000 × 100 = 30%
Rate = 30 ÷ 6 = 5%

Question 44

The difference between Compound Interest and Simple Interest for 2 years at 20% per annum is ₹480. Find the Principal.

A. ₹10,000
B. ₹11,000
C. ₹12,000
D. ₹13,000

Correct Answer: C. ₹12,000

Solution

Formula: Difference = P × R² ÷ 10000

480 = P × 400 ÷ 10000
480 = P ÷ 25
P = 480 × 25 = ₹12,000

Shortcut

At 20%, Difference = 4% of Principal
So, Principal = 480 × 25 = ₹12,000

Question 45

A person borrowed ₹40,000 at 12% Simple Interest for 3 years. Find the total Amount payable.

A. ₹53,600
B. ₹54,000
C. ₹54,400
D. ₹55,000

Correct Answer - C. ₹54,400

Solution

Simple Interest = (40,000 × 12 × 3) ÷ 100 = ₹14,400
Amount = ₹40,000 + ₹14,400 = ₹54,400

Shortcut

12 × 3 = 36%
Interest = 36% of ₹40,000 = ₹14,400
Amount = ₹54,400

Question 46 (Compound Interest)

A sum of ₹25,000 is invested at 12% Compound Interest for 2 years. Find the Amount.

A. ₹30,860
B. ₹31,160
C. ₹31,360
D. ₹31,560

Correct Answer - C. ₹31,360

Solution

Multiplier (12%, 2 years) = (1.12)² = 1.2544
Amount = 25,000 × 1.2544 = ₹31,360

Shortcut

Remember: 12% for 2 years → 1.2544
No need to apply the complete formula every time.

Question 47 (Simple Interest)

At what rate of Simple Interest will ₹18,000 become ₹22,500 in 5 years?

A. 4%
B. 5%
C. 6%
D. 7%

Correct Answer- B. 5%

Solution

Interest = 22,500 − 18,000 = ₹4,500
Rate = (4500 ×100)/(18000 ×5) = 5%

Shortcut

Interest % = 4500 ÷18000 ×100 =25%
Rate =25÷5 = 5%

Question 48 (Difference Between SI & CI)

The difference between Compound Interest and Simple Interest on a sum for 2 years at 15% is ₹675. Find the Principal.

A. ₹25,000
B. ₹28,000
C. ₹30,000
D. ₹32,000

Correct Answer - C. ₹30,000

Solution

Formula: CI − SI= (P ×15²)/10000
675 = P ×225/10000
P = (675 ×10000)/225 = ₹30,000

Shortcut

At 15% Difference = 2.25% of Principal
Principal =675÷2.25% =₹30,000

Question 49

A sum becomes ₹18,150 after 2 years at 10% Compound Interest. Find the Compound Interest earned.

A. ₹2,850
B. ₹3,000
C. ₹3,150
D. ₹3,300

Correct Answer: C. ₹3,150

Solution

Principal =18,150÷1.21 =₹15,000
Compound Interest =18,150−15,000 = ₹3,150

Shortcut

Whenever you see 10% + 2 Years
Immediately think Multiplier =1.21

Question 50

A person borrowed ₹50,000 at 8% Simple Interest for 5 years. Find the total Amount payable.

A. ₹68,000
B. ₹69,000
C. ₹70,000
D. ₹71,000

Correct Answer - C. ₹70,000

Solution

Simple Interest =(50,000 ×8 ×5)/100 =₹20,000
Amount =50,000+20,000 = ₹70,000

Shortcut

8 ×5 =40%
Interest =40% of ₹50,000 =₹20,000
Amount =₹70,000

Common Mistakes Students Make

Confusing Amount with Interest.
Forgetting to subtract the Principal in CI questions.
Using the SI formula in Compound Interest questions.
Ignoring whether compounding is yearly, half-yearly, or quarterly.
Not memorizing standard CI multipliers.