Answer
Estimated answer = 12
Exact answer = $11\frac{7}{15}$
Work Step by Step
$12\frac{2}{3}$ - $1\frac{1}{5}$
Estimation:
$12\frac{2}{3} \approx 13$
$1\frac{1}{5} \approx 1$
Therefore
$12\frac{2}{3}$ - $1\frac{1}{5}$ $\approx$ 13 - 1 = 12
Exact Calculation:
$12\frac{2}{3}$ - $1\frac{1}{5}$
= $12\frac{2\times5}{3\times5}$ - $1\frac{1\times3}{5\times3}$
(15 is the least common denominator)
= $12\frac{10}{15}$ - $1\frac{3}{15}$
= $12$ + $\frac{10}{15}$ - ($1$ + $\frac{3}{15})$
= $12$ + $\frac{10}{15}$ - $1$ - $\frac{3}{15}$
= ($12$ - $1$) + ($\frac{10}{15}$ - $\frac{3}{15}$)
(Solving whole parts separately and fractional parts separately)
= $11$ + $\frac{10 - 3}{15}$
= $11$ + $\frac{7}{15}$
= $11\frac{7}{15}$
The estimate was 12, so the exact answer of $11\frac{7}{15}$
is reasonable.
