## Basic College Mathematics (10th Edition)

estimate - 18 exact - 18$\frac{1}{3}$
34 - 15$\frac{2}{3}$ Estimate : 34 round to 34 15$\frac{2}{3}$ round to 16 So subtract 34 – 16 = 18 is the estimate answer Exact : 34 - 15$\frac{2}{3}$ It is not possible to subtract $\frac{2}{3}$ without regrouping the whole number 34 first 34 = 33 + 1 = 33 + $\frac{3}{3}$ = 33$\frac{3}{3}$ Subtract : 33$\frac{3}{3}$ - 15$\frac{2}{3}$ Subtraction of the whole number is 18 and Subtraction of the fraction is $\frac{1}{3}$ = 18$\frac{1}{3}$ The estimate was 18, so the exact answer of 18$\frac{1}{3}$ is reasonable