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15% = 15/100 = 0.15
Fifteen percent is the same as the fraction 15/100 and the decimal 0.15. They all simply mean "fifteen out of a hundred." A percent can always be written as a decimal, and a decimal can be written as a percent, like this:
0.85 = 85%
We can find any percent of a given number by changing the percent to a decimal and multiplying. One hundred percent of a number is just the number itself. Two hundred percent of a number is twice that number.
100% of 50 > 50
200% of 50 > 2 x 50 = 100
Let's find 30 percent of 400:
First change
30% to a decimal by moving the decimal point 2 places to the left.
30% = 0.30
Then multiply.
0.30 x 400 = 120
30% of 400 is 120.
Mental
Math
There's an easy way to find 10% of a number without multiplying. Just move
the decimal point in the number left by one place. Let's try it with these
numbers:
895 27 10,411
10%
of 895 = 89.5
10% of 27 = 2.7
10% of 10,411 = 1,041.1
Examples
Write each as a percent:
$6
out of $12 > $6/$12 = 0.5 = 50%
34 out of 100 > 34/100 = 0.34 = 34%
0.55 = 55%
1.2 = 120%
Find the value of n for each problem:
n
is 50% of 60 > n = 0.5 x 60 = 30
n is 4% of 33 > n = 0.04 x 33 = 1.32
n is 150% of 24 > n = 1.5 x 24 = 36
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