Finding Percents of numbers

Using the Is over Of technique in conjunction with drawing

percent bars

What do you think is the answer??

• Find 25% of 20

• Let’s draw a picture.

100%

? 25%

20

Can you solve this as a proportion? • Find 25% of 20

• What would the proportion look like?

100%

? 25%

20

10025

20x

X = 5

We can do this Mathematically by using a special

proportion...just find the following...

The Percent – it is the easiest to find.Just look for the % sign!

The “Of” number - it is always just behind the word of.

The “Is” number - it may or may not be near the “is” word. If you find the other two then what is left is the “is”!

Finding is, of or a Percent

Find the missing number by drawing a bar and using the proportion.

a) 15% of 900 is what?

100

%=

of

isUse the proportion…

15%

100900

?

10015

900x

x = 135

Finding is, of or a Percent

Find the missing number by drawing a bar and using

the proportion.

b) What % of 84 is 63?

100

%=

of

is

x%

10084

63100%

8463

X = 75%

Finding is, of or a Percent

c) 35% of what # is 7?

100

%=

of

is

Find the missing number by drawing a bar

and using the proportion.

35%

100?

7

10035

x7

X = 20

Finding is, of or a Percent

Find the missing number by drawing a bar and using the proportion.

d) 2.5% of 120 is what?

100

%=

of

is

2.5%

100120

?

1005.2

120x

x = 3

Finding is, of or a Percent

Find the missing number by drawing a bar and using the proportion.

60% of 600 is what number?

100

%=

of

is

60%100600

x10060

600x

x = 360

Homework: P. 322 #2-26 evens

You MUST show the proportion and the work you do to get the answer.