Estimate the product by rounding off each of them to nearest thousand: (a) 8478 x 2431 and (b) 3456 x 8745

Dear student,
Here is the solution of your asked query:
(a) Rounding off 8478 to nearest thousand we get 8000
And rounding off 2431 to nearest thousand we get, 2000
$$\begin{gathered} \mathrm{And} 8000\times 2000=16000000 \\ \mathrm{Therefore} 8478\times 2431 \mathrm{to} \mathrm{nearest} \mathrm{thousand} \mathrm{is} 16000000 \end{gathered}$$

(b) Rounding off 3456 to nearest thousand we get 3000
And rounding off 8745 to nearest thousand we get, 9000
$$\begin{gathered} \mathrm{And} 3000\times 9000=27000000 \\ \mathrm{Therefore} 3456\times 8745 \mathrm{to} \mathrm{nearest} \mathrm{thousand} \mathrm{is} 27000000 \end{gathered}$$
Regards