% Percentage Calculator

What is 45% of 20?

45% of 20 is 9. Use the calculator below to change either number, or see related calculations.

Enter values above to calculate.

Calculating 45% of 20: divide 45 by 100, then multiply by 20. The general formula is (X ÷ 100) × Y — works for any percentage and any number.

Percentages at this level appear in UK income tax bands and a few business margin contexts. This base value sits in the everyday range — receipts, tips, small purchases.

How it works.

Formula: (X ÷ 100) × Y.

Step by step:

  1. Divide the percentage by 100: 45 ÷ 100 = 0.45.
  2. Multiply by the number: 0.45 × 20 = 9.
Worked examples
45% of 20 = 9 — the basic calculation: divide 45 by 100 (= 0.45), then multiply by 20.
45% of 20 as a tip on a small bill — if a service charge of 45% is added to a 20 item, the extra is 9.
45% off a 20-pound item — the discount saves 9; the sale price is £11.
Related: 40% of 20 50% of 20 45% of 10 45% of 25 X% of Y calculator

Frequently asked questions

How do I calculate 45% of 20?
Divide 45 by 100, then multiply by 20. 45 ÷ 100 = 0.45; 0.45 × 20 = 9. The same formula works for any pair of numbers.
What is 45 percent of 20?
9. The full calculation: (45 ÷ 100) × 20 = 0.45 × 20 = 9.
Are there mental-maths shortcuts for percentages?
Yes. 10% of any number is the number with the decimal moved one place left. From there: 20% is double 10%; 5% is half of 10%; 15% is 10% plus half of 10%; 25% is a quarter; 50% is half. For UK shopping discounts, the 10%-anchor trick covers most quick estimates without a calculator.