Question

• How much money will Dinu pay for 32 kg iron?
• Kiran buys 1 kg iron for Rs 12 but sells it for Rs 14.
How much does she earn when she sells 32 kg iron? Rs _______

Answer 1

• Cost of 1 kg iron = Rs 14
Cost of 32 kg iron = Rs 14 × 32
= Rs 448
We do it like this:

Add the numbers in the box

$$\begin{gathered} \begin{array}{cccc}& 3& 0& 0\\ & 1& 2& 0\\ & & 2& 0\\ +& & & 8\end{array} \\ \underline{\overline{\begin{array}{cccc}& 4& 4& 8\end{array}}} \end{gathered}$$

So, Dinu will have to pay Rs 448 for 32 kg iron.

• Cost of 1 kg iron for Kiran = Rs 12

Selling price of 1 kg iron = Rs 14
Profit on selling 1 kg iron = Rs (14 − 12)
= Rs 2
Profit on selling of 32 kg iron = Rs 2 × 32
= Rs 64

We do it in the following manner:
2 × 30 = 60
2 × 2 = 4

So,
$$\begin{gathered} \begin{array}{cc}6& 0\\ +& 4\end{array} \\ \underline{\overline{\begin{array}{cc}6& 4\end{array}}} \end{gathered}$$

Thus, Kiran earns Rs 64 on selling 32 kg iron.