Percent of a Number Mentally

Mental Math Percents

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Think of the the fraction equivalent.

• 25%=1/4

• 33 1/3% = 1/3

• 20% = 1/5

• 50%=1/2

• 10% = 1/10

• 1%=1/100

Examples

Multiple Choice

What is 25% of 80?

• 20

• 40

• 25

• 16

Fill in the Blank

$$33\ \frac{1}{3}\%\ of\ 75$$  

Use the "trick of zeros"

• 20% of 70 = 2 x 7 = 14

• 60% of 30 =6 x 3 = 18

• 90% of 10 =9 x 1=9

• 30% of 5000=1500

Multiple Choice

Find 60% of 30

• 18

• 20

• 24

• 15

Fill in the Blank

Find 80% of 20

To find 1% of a number, divide by 100 (move the decimal two places to the left)

• 1% of 90 = 90/100=0.9

• 1% of 5 = 5/100=0.05

• 1% of 300=300/100=3

Multiple Choice

Find 1% of 45

• 45

• 4.5

• 0.45

• 0.045

Fill in the Blank

Find 1% of 89