Page 338 - Basic College Mathematics with Early Integers

S E C T I O N 4.4 I DIVIDING DECIMALS 315

Calculator Explorations Estimation

Calculator errors can easily be made by pressing an incor- Use estimation to determine whether each result is
rect key or by not pressing a correct key hard enough. reasonable or not.
Estimation is a valuable tool that can be used to check
calculator results. 1. 102.62 * 41.8 Result: 428.9516

Example Use estimation to determine whether 2. 174.835 , 47.9 Result: 3.65
the calculator result is reasonable or
not. (For example, a result that is not 3. 1025.68 - 125.42 Result: 900.26
reasonable can occur if proper keys are
not pressed.) 4. 562.781 + 2.96 Result: 858.781

Simplify: 82.064 , 23
Calculator display: 35.68
Solution: Round each number to the nearest 10.
Since 80 , 20 = 4, the calculator display 35.68 is not
reasonable.