Question

Match the following.

• A. $435$
• B. $345$
• C. $266$

Answer 1

We know that $29\times 15=(20+9)\times (10+5).$

$\begin{array}{ccc}\times & 20& 9\\ 10& 200& 90\\ 5& 100& 45\end{array}$

Adding the four numbers, we get:

$200100+90+\underset{–}{45}+\underset{–}{435}$

$\therefore 29\times 15=435$

Similarly, $15\times 23=(10+5)\times (20+3).$

$\begin{array}{ccc}\times & 10& 5\\ 20& 200& 100\\ 3& 30& 15\end{array}$

$200100+30+\underset{–}{15}+\underset{–}{345}$

$\therefore 15\times 23=345$

Lastly, $14\times 19=(10+4)\times (10+9).$

$\begin{array}{ccc}\times & 10& 4\\ 10& 100& 40\\ 9& 90& 36\end{array}$

$10040+90+\underset{–}{36}+\underset{–}{266}$

$\therefore 14\times 19=266$