Ten Percent of a Number Mentally

Percent Benchmarks

You don't always need a calculator to find percents of numbers!!!

Let's learn how to mentally find 50%, 10%, 20% and 5% of numbers.

To find 50% of a number without using a calculator...

just cut your number in half

Multiple Choice

To find 50% of a number, cut your number in

• half

• thirds

• fourths

Multiple Choice

Calculate 50% of 14

• 14

• 1.4

• 7

• 6

Multiple Choice

Calculate 50% of 660

• 660

• 330

• 220

• 33

Multiple Choice

Calculate 50% of 2

• 0

• 1

• 2

• 4

To find 10% of a number without using a calculator...

just move the decimal 1 time left

Fill in the Blanks

Fill in the blank:

To calculate 10% of a number, move the decimal

times left.

Multiple Choice

Calculate 10% of 59

• 59

• 5.9

• 0.59

• 0.059

Multiple Choice

Calculate 10% of 120

• 120

• 12.0

• 1.20

• 0.120

Multiple Choice

Calculate 10% of 2

• 20

• 2

• 0.2

• 0.02

Multiple Choice

Calculate 10% of 6.2

• 62

• 6.2

• 0.62

• 0.062

To find 20% of a number without using a calculator...

just move the decimal 1 time left then DOUBLE YOUR ANSWER

_{(because 20% is double of 10%)}

Multiple Choice

To calculate 20% without a calculator...

• move the decimal 1 time left

• move decimal 1 time right

• move decimal 1 time left and DOUBLE your answer

• move decimal 1 time right and DOUBLE your answer

Multiple Choice

Calculate 20% of 21

• 10% is 2.1, so 20% is 4.2

• 10% is 21, so 20% is 42

• 10% is 0.021, so 20% is 0.042

Multiple Choice

Calculate 20% of 4

• 10% is 2, so 20% is 4

• 10% is 0.4, so 20% is 0.8

• 10% is 4, so 20% is 8

Multiple Choice

Calculate 20% of 33

• 3.3

• 0.33

• 6.6

• 0.66

To find 5% of a number without using a calculator...

just move the decimal 1 time left then do HALF OF YOUR ANSWER

_{(because 5% is half of 10%)}

Multiple Select

SELECT ALL THAT APPLY:

To calculate 5%, move the decimal 1 time left then..

• move the decimal 1 time left

• move the decimal 1 time right

• cut your answer in half

• double your answer

Multiple Choice

Calculate 5% of 26

• 10% is 2.6, so 5% is 4.2

• 10% is 26, so 5% is 13

• 10% is 2.6, so 5% is 1.3

Multiple Choice

Calculate 5% of 6

• 10% is 3, so 5% is 1.5

• 10% is 0.6, so 5% is 0.3

• 10% is 0.6, so 5% is 1.2

Multiple Choice

Calculate 5% of 88

• 44

• 4.4

• 0.44

• 8.8