JAMB 2017 · UTME · Q22

Evaluate $\dfrac{0.21 \times 0.072 \times 0.00054}{0.006 \times 1.68 \times 0.063}$ .

Worked solution (try it first)

Cancel in pairs: $\frac{0.21}{0.063} = \frac{10}{3}$ , $\frac{0.072}{1.68} = \frac{3}{70}$ and $\frac{0.00054}{0.006} = 0.09$ .
Multiply: $\frac{10}{3} \times \frac{3}{70} = \frac17$ , and $\frac17 \times 0.09 = \frac{9}{700}$ .
$\frac{9}{700} = 0.012857\ldots$ , which rounds to 0.01286, option A.