First use front-end rounding to write an estimate of the answer, and then multiply fully to obtain an exact answer.
-
A)Estimate: 12, exact: 11.089
B)Estimate: 120, exact: 110.89
C)Estimate: 120, exact: 109.89
D)Estimate: 12, exact: 10.989

Question

First use front-end rounding to write an estimate of the answer, and then multiply fully to obtain an exact answer.
-
A)Estimate: 12, exact: 11.089 
B)Estimate: 120, exact: 110.89 
C)Estimate: 120, exact: 109.89 
D)Estimate: 12, exact: 10.989

Quizplus · Accepted Answer

Front-end rounding means rounding the first digit in a number to the nearest ten. In this case, the first digit is 1, so we round up to 2, making the estimate 120. When we multiply fully, we get 11.089, which is closest to the exact answer of 109.89. So, option C is the best choice. To use front-end rounding, we look at the first digit after the decimal point, which is 8. Since it is greater than or equal to 5, we round up the whole number to 110 instead of 109. Then, we drop the decimal point and multiply by 0.999: 
110 x 0.999 = 109.89 
Therefore, our estimate is 120 and our exact answer is 109.89. The only choice that matches is C.

First Use Front-End Rounding to Write an Estimate of the Answer