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📚 Part of: Percentages guide

Fractions, Decimals and Percents: One Number, Three Outfits

3/8, 0.375 and 37.5% are the same number in three outfits. Learn to switch between them without thinking, and half of CLAT Quant turns into mental maths.

RR ✔ Reviewed by Ravi Raj Singh · BTech (Computer Science); MA English, NET-qualified
3
past CLAT Qs
11 min
read
1
live calculator
Practise Percentages drills →
📑 On this page
⚡ The short answer
A fraction, a decimal and a percent are one number in three outfits. Fraction → percent: × 100 (3/8 = 37.5%). Percent → decimal: ÷ 100, point two places left (37.5% = 0.375). Percent → fraction: put it over 100 and simplify. Speed comes from knowing the fraction families. The trap: 0.5% is 0.005, not 0.5.
🎬 The 30-second story
The report-card fight
1
“42 out of 50 in maths. Beat that.”
📝
Aarav
Results day.
2
“17 out of 20 in the English quiz. Mine's higher.”
📋
Zoya
Zoya, unbothered.
3
“My practice app says accuracy 0.86. Is that good?”
📱
Meher
Meher holds up her phone.
4
“Different totals, a decimal… this can't be compared!”
🤯
Aarav
Tara walks in with chai.
Tara's maths: Put everyone in the same outfit: out of 100. 42/50 = 84%, 17/20 = 85%, 0.86 = 86%. Meher wins by a point. A percent is just a fraction with the bottom fixed at 100, which is why it makes things comparable.

Are fractions, decimals and percents really the same number?

Yes. "Percent" is Latin-ish for per hundred. So 85% literally means 85/100. A decimal is a fraction with 10, 100 or 1,000 at the bottom, written with a point instead. Three ways to write one quantity, like ₹1, 100 paise and one rupee coin.

🟦 Picture the percent
One shaded area, three names
3/4
3 of every 4 = 75 of 100 = 75% = 0.75
1st quarter2nd3rd
7/20
7/20 = 35/100 = 35% = 0.35
0.6
6 tenths = 60 hundredths = 60% = 3/5

Each grid is 100 squares, so the count of shaded squares is the percent.

Each outfit has a job. Percents compare (84 vs 85 vs 86). Fractions multiply in your head (37.5% of 640 is 640 ÷ 8 × 3). Decimals chain changes (× 1.1, then × 0.9). Switch to whichever suits the question.

How do you convert a fraction to a percentage, and back?

To ask "what percent is 3/8?" is to ask "3/8 = ?/100". Multiply both sides by 100 and you get 37.5. Writing × 100 and then % (÷ 100) multiplies by 1: the number stays, only the outfit changes.

🧮 The formula
Fraction to percent
🍕
3/8
the fraction
×
💯
100
"per hundred"
=
🎯
37.5%
= 0.375 as a decimal

Then drop the % and shift the point two places left for the decimal.

From → toDo thisExample
Fraction → %× 1003/8 × 100 = 37.5%
% → fractionPut over 100, simplify35% = 35/100 = 7/20
% → decimal÷ 100: point two places left4.5% = 0.045
Decimal → %× 100: point two places right0.875 = 87.5%
Decimal → fractionOver 10, 100 or 1,000, simplify0.36 = 36/100 = 9/25
Fraction → decimalDivide top by bottom7/40 = 0.175
→ scroll to see more
💡 Scale the bottom to 100
If the denominator divides 100, skip the division. 7/20: multiply top and bottom by 5 → 35/100 = 35%. 9/25 → 36/100 = 36%. If it divides 1,000, use that: 7/40 = 175/1000 = 17.5%.

How do you use conversions inside a real sum?

Four problems, climbing. Watch where each one changes outfit, and why.

✍️ Worked example Warm-up ⏱ 15 sec
The quiz score
Meher scores 7 out of 40 on a brutal current-affairs quiz. Write it as a decimal and a percent.
  1. 1
    7 ÷ 40 = 0.175.
  2. 2
    × 100: 17.5%.
Answer: 0.175, or 17.5%.
⚡ The exam-hall shortcut
1/40 = 2.5% (half of 1/20 = 5%). So 7/40 = 7 × 2.5 = 17.5%. No long division.
✍️ Worked example CLAT level ⏱ 20 sec
The phone down payment
Aarav's ₹54,000 phone needs a down payment of 16⅔%, and the rest goes on EMI. How much is on EMI?
  1. 1
    16⅔% is 1/6 (half of 33⅓% = 1/3).
  2. 2
    Down payment = 54,000 ÷ 6 = ₹9,000.
  3. 3
    EMI amount = 54,000 − 9,000 = ₹45,000.
Answer: ₹45,000 on EMI.
⚡ The exam-hall shortcut
EMI share = 1 − 1/6 = 5/6. 54,000 ÷ 6 × 5 = 45,000 in one line.
✍️ Worked example CLAT level ⏱ 40 sec
Which slice is biggest?
Four friends describe their study time as a share of the day's free time: 5/7, 0.7, 72% and 13/18. Whose share is largest?
  1. 1
    Put everyone in percent. 5/7 = 1 − 2/7 = 100 − 28.57 = 71.43%.
  2. 2
    0.7 = 70%; 72% stays 72%.
  3. 3
    13/18 = 1 − 5/18. 5/18 = 27.78%, so 13/18 = 72.22%.
Answer: 13/18 (72.22%) edges out 72%.
⚡ The exam-hall shortcut
When a fraction is close to 1, convert the gap: 5/18 is 2.5 × 1/9 = 2.5 × 11.11 = 27.78%. Subtracting from 100 is faster than dividing 13 by 18.
✍️ Worked example Tricky ⏱ 30 sec
The strike rate
Kabir, the local club's opener, has a strike rate of 137.5 after facing 40 balls. How many runs has he scored?
  1. 1
    Strike rate is runs per 100 balls: a percent in disguise. 137.5 per 100 = 1.375 runs a ball.
  2. 2
    1.375 = 1 + 0.375 = 1 + 3/8 = 11/8.
  3. 3
    Runs = 40 × 11/8 = 5 × 11 = 55.
Answer: 55 runs.
⚡ The exam-hall shortcut
Percents can pass 100. Spot 37.5 = 3/8 and the 40 balls divide by 8 cleanly.
🎛️ Try it yourself — change any number
Try it: any fraction, two outfits
As a percent
72.22%
As a decimal
0.7222
13 ÷ 18 × 100 = 72.22%
13/18 gives 72.22%. Now try the story: 42/50, 17/20. Then 1/7, 2/7 and 3/7, and watch 14.29 multiply.

Which fraction to percentage table should you memorise?

Don't learn 30 random pairs. Learn one anchor per family, then multiply or halve. Know 1/8 = 12.5% and you get 3/8, 5/8 and 7/8 for free; halve it and you have 1/16 = 6.25%.

FamilyAnchorFree multiplesHalve it
Eighths1/8 = 12.5%3/8 = 37.5%, 5/8 = 62.5%, 7/8 = 87.5%1/16 = 6.25%
Thirds1/3 = 33.33%2/3 = 66.67%1/6 = 16.67%
Sixths1/6 = 16.67%5/6 = 83.33%1/12 = 8.33%
Sevenths1/7 = 14.29%2/7 = 28.57%, 3/7 = 42.86%1/14 = 7.14%
Ninths1/9 = 11.11%2/9 = 22.22%, 4/9 = 44.44%1/18 = 5.56%
Elevenths1/11 = 9.09%2/11 = 18.18%, 3/11 = 27.27%1/22 = 4.55%
Twentieths1/20 = 5%3/20 = 15%, 7/20 = 35%1/40 = 2.5%
→ scroll to see more

Now run the table backwards. A percent that looks ugly is usually a friendly fraction: 62.5% of 1,280 is 5/8 of 1,280 = 160 × 5 = 800. Divide first, then multiply, and the numbers stay small.

ChangeMultiplier₹480 becomes
+25%× 5/4₹600
−20%× 4/5₹384
+12.5%× 9/8₹540
−37.5%× 5/8₹300
+33⅓%× 4/3₹640
−16⅔%× 5/6₹400
→ scroll to see more
📌 Every % change is a fraction
Increase by x%: multiply by (100 + x)/100. +12.5% = 112.5/100 = 9/8. Decrease by x%: (100 − x)/100. −37.5% = 62.5/100 = 5/8. This is why the eighths family pays off on every percentage page.

How does CLAT hide conversions in a caselet?

Caselets hand you a total and a list of percent shares, then ask for rupees. Every answer is "share × total", and the work is choosing the cleanest route. CLAT 2025 did exactly this with Mr Das: salary ₹9,228 plus a 10% house rent allowance, so income = 9,228 × 1.1 = ₹10,150.80.

📊 The data
Mr Das's month in rupees (CLAT 2025, passage XXI)
Food 25%
₹2,537.7
Education 23%
₹2,334.68
Rent 18%
₹1,827.14
Medical 13%
₹1,319.6
Savings 12%
₹1,218.1
Entertainment 9%
₹913.57

Find 1% once (₹101.508); each bar is that × its share. Friendly shares skip even that: 25% is income ÷ 4. The shares add to 100%, so the bars add back to the full income.

What are the common conversion traps?

🧭 Decision flow
Which outfit should this number wear?
❓ Is the percent a friendly fraction (12.5, 16⅔, 25, 37.5…)?
Yes →
Fraction: divide the total first, then multiply.
No ↓
❓ Are you comparing several shares?
Yes →
Percent: put all of them out of 100.
No ↓
❓ Are you chaining changes (+10%, then −5%)?
Yes →
Decimal multipliers: × 1.1 × 0.95.
No →
Find 1% of the total, then scale up.
⚠️ 1/7 is not 14%
1/7 = 14.2857…%. Over a total of 70,000, 14% gives 9,800 but 1/7 gives 10,000. For sevenths, ninths and elevenths, work in the fraction and convert only at the end.

How has CLAT asked fraction-percent conversions?

📝 Asked in CLAT 2025 · Q115 Percent of a total with an allowance
Mr. Das is working in a construction company. … His total monthly income includes a salary of Rs. 9228/- and a 10% house rent allowance. … Out of his total monthly income, he spends 25% on food expenses, 18% on paying the house-rent, 9% on entertainment, 23% on the education of his child, 13% on medical expenses, and he saves 12% of his total monthly income.

How much money does Mr. Das pay as the house-rent?

ARs. 1827 /-
BRs. 1661 /-
CRs. 1783 /-
DRs. 1935 /-
Reveal answer + reasoning
Answer: A
Base first: income = salary + 10% HRA = 9,228 × 1.1 = ₹10,150.80.
Rent = 18% = 0.18 × 10,150.80 = ₹1,827.14 → ₹1,827. Answer A, about 40 seconds.
Fast route: 1% = ₹101.51, so 18% = 101.51 × 18 ≈ 1,827.
Why the others fail
  • B — ₹1,661 is 18% of the salary alone (9,228 × 0.18 = 1,661.04). It forgets the HRA in the base.
  • C — ₹1,783 is about 17.6% of income; no correct route gives it.
  • D — ₹1,935 is about 19.1% of income; a guess above the true figure.
📝 Asked in CLAT 2025 · Q120 Adding shares before converting
(Same passage: income = salary of Rs. 9228/- plus a 10% house rent allowance; food 25%, house-rent 18%, entertainment 9%, education 23%, medical 13%, savings 12%.)

How much total money has he spent on food and entertainment?

ARs. 3541/-
BRs. 3461/-
CRs. 3371/-
DNone of the above
Reveal answer + reasoning
Answer: D
Add the shares first: 25% + 9% = 34%. One multiplication: 0.34 × 10,150.80 = ₹3,451.27.
None of A, B or C equals ₹3,451, so the answer is D. About 45 seconds.
Check another way: food ₹2,537.70 + entertainment ₹913.57 = ₹3,451.27.
Why the others fail
  • A — ₹3,541 swaps two digits of the true ₹3,451. A bait for students who half-remember their working.
  • B — ₹3,461 is ₹10 off: close, but CLAT asked for the exact amount and the rest of the set uses exact rupees.
  • C — ₹3,371 sits between 34% of the bare salary (₹3,137.52) and the true ₹3,451.27; no route lands on it.
📝 Asked in CLAT 2021 · Q147 Add shares, then use a fraction
… in the year 2019, he spent 23 per cent of his income on food, 15 per cent on Housing, and 12 per cent on his child's education. For his transport, he spent 10 per cent, and for clothing of his family he spent 10 per cent. In the meanwhile, Mr. Abishek also saved 15 per cent of his income in the year 2019, and the remaining 20 per cent of expenditure he kept as other spendings. …

If the total amount spent was ₹ 56,000, how much money was spent on clothing and housing together?

A₹ 11,500
B₹12,500
C₹14,000
D₹ 15,000
Reveal answer + reasoning
Answer: C
Clothing 10% + housing 15% = 25% = 1/4. A quarter of 56,000 = ₹14,000. Answer C, about 10 seconds.
The slow route (5,600 + 8,400) gets there too, but spotting 25% as 1/4 is the whole lesson of this page.
Note: the passage's shares add to 105%, a slip in the paper. The key simply takes each share of ₹56,000, so do that.
Why the others fail
  • A — ₹11,500 is not a quarter of 56,000 (that would need a total of 46,000).
  • B — ₹12,500 would need a total of 50,000.
  • D — ₹15,000 is a quarter of 60,000; it rounds the total up.

Fraction, decimal or percent: can you spot the myth?

💥 Myth vs fact
Myth vs fact
🙅 Myth
0.5% and 0.5 are the same.
Tap to bust it →
✅ Fact
0.5% = 0.005. It is 100 times smaller than 0.5.
🙅 Myth
33% is one-third.
Tap to bust it →
✅ Fact
Close, not equal. 1/3 = 33.33…%. On 9,000 the gap is 30, enough to split two options.
🙅 Myth
A percent can't be more than 100.
Tap to bust it →
✅ Fact
5/4 = 125%. A strike rate of 137.5 is 137.5% of the balls faced.
🙅 Myth
20% of 30% is 50%, or 600%.
Tap to bust it →
✅ Fact
Multiply the decimals: 0.2 × 0.3 = 0.06 = 6%.
🎯 Quick quiz
Quick check: 5 questions
0 / 5

Q1. What is 0.045 as a percent?

A college fest sold 87.5% of its 2,400 passes.

Q2. How many passes were sold?

Q3. Which is the largest: 3/11, 0.28, 27% or 2/7?

A phone shop charges 0.5% a month on an unpaid ₹18,000.

Q4. What is the monthly charge?

A creator's followers this month are 9/8 of last month's.

Q5. By what percent did they grow?

🎯 Conversions in a nutshell
  • Fraction, decimal and percent are one number: 3/8 = 0.375 = 37.5%.
  • Fraction → %: × 100. % → decimal: ÷ 100. % → fraction: over 100, simplify.
  • Learn one anchor per family (1/8, 1/3, 1/7, 1/9, 1/11, 1/20) and build the rest.
  • Friendly percent? Use the fraction: divide first, then multiply.
  • Watch the decimal: 0.5% = 0.005, and 1/3 is not exactly 33%.
📎 Formula card
  • Fraction → % = fraction × 100 · % → decimal = ÷ 100 · % → fraction = % ÷ 100, simplify
  • 1/8 = 12.5% · 3/8 = 37.5% · 5/8 = 62.5% · 7/8 = 87.5% · 1/16 = 6.25%
  • 1/3 = 33.33% · 2/3 = 66.67% · 1/6 = 16.67% · 5/6 = 83.33% · 1/12 = 8.33%
  • 1/7 = 14.29% · 2/7 = 28.57% · 1/9 = 11.11% · 1/11 = 9.09% · 1/40 = 2.5%
  • Repeating decimals: 0.ab ab… = ab/99 (0.4545… = 5/11)
  • +x% = × (100 + x)/100: +25% = × 5/4, +12.5% = × 9/8, −20% = × 4/5

Frequently asked questions

How do you convert a fraction to a percentage?
Multiply the fraction by 100 and add the % sign. 3/8 × 100 = 37.5%. If the denominator divides 100, scale it up instead: 7/20 = 35/100 = 35%. For an awkward denominator, divide top by bottom to get a decimal, then move the point two places right.
Which fraction to percentage table should I memorise for CLAT?
Memorise one anchor per family: 1/8 = 12.5%, 1/3 = 33.33%, 1/6 = 16.67%, 1/7 = 14.29%, 1/9 = 11.11%, 1/11 = 9.09% and 1/20 = 5%. Multiply each for the rest, so 3/8 = 37.5% and 2/7 = 28.57%, and halve them for sixteenths, twelfths and fourteenths.
How do you convert a percentage to a decimal?
Divide by 100, which means moving the decimal point two places to the left. 45% becomes 0.45, 4.5% becomes 0.045 and 0.5% becomes 0.005. The last one trips people most: half a percent is five thousandths, not one half. On ₹18,000, that is ₹90, not ₹9,000.
What is 1/7 as a percentage?
1/7 is 14.2857…%, usually written 14.29%. Multiples follow: 2/7 = 28.57%, 3/7 = 42.86%. Don't round it to 14% on large totals: 14% of 70,000 is 9,800, while 1/7 of 70,000 is exactly 10,000, a gap big enough to pick the wrong option.
Is 33% the same as one-third?
No. One-third is 33.33…%, a repeating decimal. 33% of 9,000 is 2,970, while 1/3 of 9,000 is 3,000. When a question says 33⅓% or 33.33%, use the fraction 1/3 and divide by 3; it is faster, exact and kinder to your nerves.

Keep going

📚
Part of the chapter
Percentages for CLAT Quantitative Techniques
See how this topic fits the whole of Percentages →

Connected topics in other chapters

Every topic in Percentages

  1. 1.Fractions, Decimals and Percents: One Number, Three Outfits (you're here)
  2. 2.Percentage Increase, Decrease and "% More Than"
  3. 3.Successive Percentage Change: the a + b + ab/100 Rule
  4. 4.Reverse Percentage: Finding the Original Number
  5. 5.Population Growth and Depreciation
  6. 6.Percentage Points vs Percent: Two Answers, One Change
  7. 7.Budgets and Pie Charts: Percentage Share
  8. 8.Caselet DI: Turning a CLAT Quant Passage into a Table
  9. 9.Percentage Shortcuts and Approximation

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