Decimal
0.2 × 20 = 4
Fraction
⅕ of 20 = 4
Equation
(20 ÷ 100) × 20 = 4
How to calculate 20% of 20
Two steps — convert to a decimal, then multiply.
- 1
Convert the percentage to a decimal
20 ÷ 100 = 0.2
- 2
Multiply the original number by the decimal
0.2 × 20 = 4
Where 20% of 20 comes up in practice
A 20% tip on a $20 restaurant bill comes out to $4.00, bringing the total to $24.00.
How to read this number
- 20% is the modern US standard tip for good service — $4.00 on a $20.00 bill brings the total to $24.00.
Mental math shortcut
⅕ — divide by 5. Or take 10% and double it.
The same calculation, expressed three ways
Knowing one of these gives you the other two — handy when a problem is phrased differently to what you typed.
- 4 is 20% of 20
- 4 out of 20 = 20%
- 20% off $20.00 = $16.00
Frequently asked
Common follow-up questions for 20% of 20.
Yes — multiplying by the decimal form (0.2) is exactly what "20% of 20" means. 20 × 0.2 = 4.
20% equals ⅕. So ⅕ of 20 = 4, which is the same answer reached the long way.
No — 20% of $20 is the discount amount itself ($4.00). 20% off $20 means the sale price is $16.00 (the original price minus the discount).
⅕ — divide by 5. Or take 10% and double it. For 20% of 20 that gives 4 directly.
The number is 20. To work it out, divide 4 by 0.2: 4 ÷ 0.2 = 20.
Total = $24.00. The bill ($20) plus a 20% tip ($4.00) = $24.00.
Need a different calculation?
Use the full Percentage Calculator — five modes including reverse calculations, percentage change, and percentage difference.
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