Percent of a Number

By Barb Leach

7th Grade Mathematics

Owensville Middle School

General Objective

MA, NO, 2, C, 07

The student will solve problems using ratio and proportion in consumer situations.

When will we use this?

Salespeople need to find percents quickly to determine discounts.

People working at oil refineries make gasolines by mixing percents of different chemical compounds.

Printers combine different percents of four basic colors to produce colors you see in books.

How to find the percent of a number

Method 1 Use A Proportion (always put the percent number over 100 equal to the part over the total)

Find the number, round to the nearest tenth.

What number is 60% of 150?

60 = w

100 150

100 w = 9000

100 100

w = 90

How?

Method 2 Use Multiplication (change the percent to a decimal, then multiply)

Find the number, round to the nearest tenth.

Find 80% of 90.5.

.8 x 90.5 = n

72.4 = n

Practice

Use either method to show how you arrived at your answer.

SMART Notebook File

Practice FindingPercent of a Number

Assessment

Practice Worksheet

Resources/References

Glencoe Mathematics Applications and Connections Course 2

Scott Foresman-Addison Wesley Middle School Math Course 2