Question

Renu purchased 13 kg of steel. Guess the amount that she paid if one kg steel costs ₹62.

• A. Less than ₹600
• B. More than ₹780
• C. More than ₹900
• D. In between ₹400 and ₹500

Answer 1

The correct option is B More than ₹780

To get the idea of amount paid we can simplify the number a bit
so to guess the amount paid we need to multiply ₹62 x 13
but we can use ₹60 in place of ₹62, since ₹60 x 13 is easier to calculate.

₹60 x 13 can be calculated as 6x13 and then a zero can be added in the end.
$$\begin{array}{ccc}\times & 10& 3\\ 6& 6\times 10=60& 6\times 3=18\end{array}$$
So the multiplication is (60+18) x 10
= ₹780

Now that we know that 62 is more than 60, so 62 x 13 will also be more than
60 x 13 = 780
So she paid more than ₹780