Sumwise

What is 90 Percent of 42?

90% of 42 = 37.8

Result
37.8
Remaining
4.2
90% as decimal
0.9
42 + 90%
79.8

Sumwise · Maintained by Theo Abbott (pen name) · automated checks · Data: exact arithmetic; unit definitions from NIST SP 811 · Updated · How the checks work

How to work it out

  1. Turn the percentage into a decimal: 90 ÷ 100 = 0.9
  2. Multiply: 0.9 × 42 = 37.8
  3. Check: Work backwards: 37.8 ÷ 42 × 100 = 90%.

Another method. As a proportion of part to whole: 90/100 = part/42, so part = 90 × 42 ÷ 100 = 37.8. Both methods always give the same answer.

In a spreadsheet: =90%*42. Forgetting to divide the percentage by 100 makes the answer 100 times too big. Note that x% of y always equals y% of x.

What the result means

37.8 is the 90% share of 42. The remaining 10% is 4.2, and the two parts add back up to 42.

Discounts: 90% off an item priced $42 saves $37.8, so you pay $4.2.

Adding and taking away 90%

Increasing 42 by 90% gives 79.8 and decreasing it by 90% gives 4.2. These do not cancel out: raising 42 by 90% and then lowering the result by 90% ends at 7.98, because the second 90% is taken of a bigger number.

Related results

Results for nearby numbers
5% of 42

5% of 42 = 2.1

10% of 42

10% of 42 = 4.2

15% of 42

15% of 42 = 6.3

20% of 42

20% of 42 = 8.4

25% of 42

25% of 42 = 10.5

50% of 42

50% of 42 = 21

75% of 42

75% of 42 = 31.5

The other way round: 42% of 90. 90% of 42 and 42% of 90 are always equal (both are 90 × 42 ÷ 100 = 37.8), so you can swap the numbers when one order is easier to work out in your head.

Practice

18% of 11
Show answer

18% of 11 = 1.98

9% of 46
Show answer

9% of 46 = 4.14

32% of 18
Show answer

32% of 18 = 5.76

85% of 48
Show answer

85% of 48 = 40.8

22% of 86
Show answer

22% of 86 = 18.92

97% of 10
Show answer

97% of 10 = 9.7

Calculate another

How answers are calculated and checked: methodology.

Questions

What is 90 Percent of 42?

90% of 42 is 37.8. Formula, steps and practice examples.

What is 90% off 42?

4.2. Taking 90% off leaves 10% of 42.

What is 42 plus 90%?

79.8. Adding 90% is the same as multiplying by 1.9.