Reviewed by Phoebe Belza-Barrientos
What is 20% of 90?
Answer: 20% of 90 is 18
Calculating a percentage of a number is a common math operation that helps us determine a part of the whole amount. In this case, finding 20% of 90 means determining what value represents 20 parts out of every 100 parts of 90.
Methods
Math Tutor Explanation Using the Percent Formula
The percent formula allows you to multiply the base number by the percentage expressed as a decimal to find the part.
Step 1: Step 1: Convert 20% to decimal by dividing by 100 (20 ÷ 100 = 0.2)
Step 2: Step 2: Multiply 0.2 by 90
Math Tutor Explanation Using Proportion Method
A proportion can set 20% over 100 equal to x over 90 to find the value directly.
Step 1: Step 1: Set up the equation as 20/100 = x/90
Step 2: Step 2: Cross-multiply to get 20 × 90 = 100 × x
Step 1:
Step 2:
Math Tutor suggests: More Practice with Percentages
Strengthen your skills in finding percentages of numbers with these related exercises.
FAQ on Percentage Calculations
How do I convert a percentage to a decimal?
Divide the percentage by 100; for example, 20% becomes 0.2.
What is the general formula for finding a percentage of a number?
Multiply the number by the percentage as a decimal.
Can percentages be larger than 100?
Yes, percentages greater than 100 indicate a value larger than the original number.
How can I check my percentage calculation?
You can reverse the process by dividing your answer by the original number and multiplying by 100 to see if you get the original percentage.
Math & reading from 1st to 9th grade
Looking for homework support for your child?
Choose kid's grade
