Decimal
0.18 × 30 = 5.4
Fraction
— (no clean fraction)
Equation
(18 ÷ 100) × 30 = 5.4
How to calculate 18% of 30
Two steps — convert to a decimal, then multiply.
- 1
Convert the percentage to a decimal
18 ÷ 100 = 0.18
- 2
Multiply the original number by the decimal
0.18 × 30 = 5.4
Where 18% of 30 comes up in practice
A 18% tip on a $30 restaurant bill comes out to $5.40, bringing the total to $35.40.
How to read this number
- 18% is common as an auto-gratuity for parties of 6+ at US restaurants. $5.40 on $30.00 is right in line with that benchmark.
Mental math shortcut
10% + 8% — or, take 20% and shave a touch off.
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.
- 5.4 is 18% of 30
- 5.4 out of 30 = 18%
- 18% off $30.00 = $24.60
Frequently asked
Common follow-up questions for 18% of 30.
Yes — multiplying by the decimal form (0.18) is exactly what "18% of 30" means. 30 × 0.18 = 5.4.
No — 18% of $30 is the discount amount itself ($5.40). 18% off $30 means the sale price is $24.60 (the original price minus the discount).
10% + 8% — or, take 20% and shave a touch off. For 18% of 30 that gives 5.4 directly.
The number is 30. To work it out, divide 5.4 by 0.18: 5.4 ÷ 0.18 = 30.
Total = $35.40. The bill ($30) plus a 18% tip ($5.40) = $35.40.
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