What Is X% of Y? (Step-by-Step Explanation)

Quick Answer: To find X% of Y, multiply Y by X and divide by 100. The formula is: (Y × X) ÷ 100 = Result

For example, 20% of 150 = (150 × 20) ÷ 100 = 30

Need an instant answer? Use our percentage calculator - just enter your numbers and get the result immediately.

The Formula Explained

Finding X percent of Y means calculating what portion of Y equals X out of 100. Here's the universal formula:

X% of Y = (Y × X) ÷ 100

Or equivalently:

X% of Y = Y × (X ÷ 100)

Both formulas give identical results. Choose whichever feels more natural to you.

Step-by-Step Method

Follow these three simple steps to find any percentage of any number:

Step 1: Take your percentage (X) and divide it by 100 to convert it to a decimal.

Step 2: Multiply that decimal by your number (Y).

Step 3: The result is X% of Y.

Example: What is 20% of 150?

Step 1: Convert 20% to decimal → 20 ÷ 100 = 0.20

Step 2: Multiply → 0.20 × 150 = 30

Answer: 20% of 150 is 30

Common Percentage Calculations

Here are frequently searched percentage problems solved:

Mental Math Shortcuts

You don't always need a calculator. Use these tricks for quick estimates:

For 10% - Move the decimal point one place to the left.

• 10% of 250 = 25

• 10% of 80 = 8

For 5% - Find 10% and divide by 2.

• 5% of 200 = 20 ÷ 2 = 10

For 20% - Find 10% and double it.

• 20% of 150 = 15 × 2 = 30

For 25% - Divide by 4.

• 25% of 80 = 80 ÷ 4 = 20

For 50% - Divide by 2.

• 50% of 120 = 60

For 1% - Move the decimal two places to the left.

• 1% of 500 = 5

Combine shortcuts for other percentages:

• 15% = 10% + 5%

• 30% = 3 × 10%

• 75% = 50% + 25%

Why This Formula Works

Percent literally means "per hundred." When you ask "What is 20% of 150?", you're really asking: "If I divided 150 into 100 equal parts, what would 20 of those parts equal?"

Since each part equals 150 ÷ 100 = 1.5, then 20 parts equal 20 × 1.5 = 30.

This is mathematically identical to (150 × 20) ÷ 100 = 30.

Real-Life Applications

Shopping discounts: A $150 item is 20% off. The discount is 20% of 150 = $30. You pay $150 - $30 = $120.

Tips at restaurants: Your bill is $80 and you want to leave a 15% tip. That's 15% of 80 = $12.

Sales tax: An item costs $50 and tax is 8%. The tax amount is 8% of 50 = $4. Total: $54.

Test scores: You got 45 questions right out of 60. That's (45 ÷ 60) × 100 = 75%.

Savings goals: You want to save 20% of your $3,000 monthly income. That's 20% of 3,000 = $600.

Frequently Asked Questions

How do I find X% of Y without a calculator?

Use the mental math shortcuts above. For most percentages, find 10% first (move decimal left), then adjust from there.

What if X is greater than 100?

The formula works the same way. 150% of 80 = 80 × 1.50 = 120. A percentage over 100% simply means more than the original amount.

Is "X% of Y" the same as "Y% of X"?

Yes! Due to how multiplication works, 20% of 50 equals 50% of 20. Both equal 10. This trick can sometimes make mental math easier.

How do I reverse this? (Find what percent X is of Y)

Use a different formula: (X ÷ Y) × 100 = percentage. For example, 30 is what percent of 150? → (30 ÷ 150) × 100 = 20%.

Calculate Any Percentage Instantly

Skip the math entirely. Our free percentage calculator solves "What is X% of Y?" questions in one click. Just enter your percentage and number to get an instant, accurate answer.

Bookmark this page for quick reference, or use our calculator whenever you need to find a percentage of any number.