Unit 11

Addition of Decimal Fractions

• A decimal number is a number with a decimal point in it.

• The decimal point separates the whole number part of the number from the fraction part. The whole number is to the left of the decimal point, the fraction is to the right of the decimal point.

• Each number position of the fraction part has a name, just as each position of a whole number. (tenths, hundredths, thousandths, ten-thousandths, etc.)

Basic Principles

Adding decimal numbers is just like adding whole numbers, withone additional concern. When writing the numbers, line up thedecimal points.

Find the sum of 233.45, 18.9, and 506.807.

Remember: When adding decimal fractions, always make sure that the decimal points are lined u one under the other.

Estimating:

The estimated answer is 720. Using a calculator, entering 233.45 + 18.9 + 506.807 = gives 759.157, which is close to 720

Three shims are being used to align a compressor and motor. The thickness of the shims are 0.43 inches, 0.28 inches, and 0.03 inches. What size single shim can replace the three?

Even though the problem has small numbers, we round them offto one numeral each.

Unit 11, Problem 15

Unit 11, Problem 19

Unit 11, Problem 20

Unit 11, Problem 20

Unit 11, Problem 21