Add And Subtract Decimals

Adding and subtracting decimals is the almost the same as adding and subtracting whole numbers.

Be careful...



Example One - Addition

What is the sum of 3.45 and 67.8? (Line up the columns. Fill in any blank decimal places with zeros.)

Answer:

3.45
+ 67.80
71.25

Example Two - Subtraction

What is the difference between 67.8 and 3.45? (Line up the columns. Fill in any blank decimal places with zeros.)

Answer:

67.80
– 3.45
64.35

Question - Novelty Contact Lenses

Contact Lens

At c-r-a-z-y-e-y-e store, I bought 3 pairs of novelty contact lenses - Cats Eye for $58.95, Rainbow Eye for $38.78, and Green Dragon for $29.55. How much change did I receive from $150 cash?

Answer
$22.72 to nearest cent; $22.70 cash

Question - Feeler Gauge

Feeler Gauge

A feeler gauge is a tool used by engineers and car mechanics for measuring gap widths such as the gap in a spark plug. The six gauges have widths of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm and 0.6 mm. Which combination of these would be used to measure a gap of 1.5 mm?

Answer
0.4 mm + 0.5 mm + 0.6 mm = 1.5 mm