Вычислим a·b и a:b, если a = 8 · 10n+2, b = 4 · 10n+1:
- $$a \cdot b = (8 \cdot 10^{n+2}) \cdot (4 \cdot 10^{n+1}) = 8 \cdot 4 \cdot 10^{n+2+n+1} = 32 \cdot 10^{2n+3}$$
- $$\frac{a}{b} = \frac{8 \cdot 10^{n+2}}{4 \cdot 10^{n+1}} = \frac{8}{4} \cdot \frac{10^{n+2}}{10^{n+1}} = 2 \cdot 10^{n+2-(n+1)} = 2 \cdot 10^{n+2-n-1} = 2 \cdot 10^1 = 20$$
Ответ: $$a \cdot b = 32 \cdot 10^{2n+3}$$, $$a:b = 20$$