Percentage Calculator

A percentage is a fraction dressed for comparison. "Per cent" literally means "out of a hundred", and the % sign itself evolved from the habit of writing the Italian "per cento" as a slashed fraction — the "/100" shorthand that fifteenth-century printers slowly condensed into the symbol we use today. Because everything is scaled to 100, percentages let you compare very different quantities — a mark scheme out of 120, a ₹40,000 budget, a bill of ₹540 — on a single common scale.

The core question: X% of Y

The basic operation is one multiplication:

Result = value × percent ÷ 100

Worked example

What is 15% of 200?

200 × 15 ÷ 100 = 3000 ÷ 100 = 30

So 15% of 200 is 30. The calculator repeats this for any two numbers you enter — percent first, value second.

Why divide by 100?

The "%" is a compact device for writing "÷ 100". 15% is 0.15 as a decimal, so "15% of 200" is simply 200 × 0.15 = 30. The calculator keeps the percentage as a whole number and does the dividing by 100 at the end; the arithmetic underneath is identical either way.

Mental-math anchors

Because every percent is a fragment of 100, a few anchors cover most everyday estimates:

• 10% of anything = move the decimal one place left (10% of 2,000 = 200)
• 5% = half of 10%
• 1% = move the decimal two places (1% of 2,000 = 20)
• 50% = half, 25% = quarter, 33% ≈ third

Three-quarters of day-to-day percentage arithmetic can be assembled from these fragments alone.

Everyday uses

• Discounts — "25% off ₹2,000": 2,000 × 25 ÷ 100 = ₹500 off, so ₹1,500 to pay.
• Exams — scoring 85% in a 120-mark paper: 120 × 85 ÷ 100 = 102 marks.
• Tips — 10% of a ₹540 bill is ₹54.
• Budgeting — 30% of a ₹40,000 salary set aside for rent: ₹12,000.
• Data and surveys — expressing one group's share of the whole in per-hundred terms.

Fraction shortcuts worth memorizing

Because every percent is a fraction out of 100, the classic fractions translate instantly:

• 1/2 = 50%, 1/4 = 25%, 1/5 = 20%, 1/8 = 12.5%
• 1/3 ≈ 33.3%, 1/6 ≈ 16.7%, 1/12 ≈ 8.3%

Spotting "a quarter" or "a fifth" in a real-world sentence lets you answer without any calculator, and it makes errors leap out — a 12.5% figure where a quarter was expected is an instant red flag.

The family of four

Percentages form a four-way triangle, each direction with its own tool:

1. Percent known, whole known → part? This calculator (15% of 200).
2. Part and whole known → percent? The what percent of tool (30 is what % of 200?).
3. Part and percent known → whole? The reverse percentage tool (30 is 15% of what?).
4. Two readings known → change or difference? The percentage change and percentage difference calculators.

Common mistakes

• Chaining percentages without re-basing: "15% more" then "15% off" is not "back to the start" — 1.15 × 0.85 = 0.9775, a net loss.
• Mistaking the decimal: 25% is 0.25, never 25 — using 25 as the multiplier returns 25 times the true answer.
• Expecting a cap at 100 when the base allows otherwise — percentages above 100 are valid on open scales.
• Forgetting which number is the whole: "scoring 85% in a 120-mark exam" uses 120 as the whole and 85% as the fraction.

The calculator answers the first leg of that triangle instantly; its siblings cover the other three.