# Ex.12.2 Q4 Exponents and Powers - NCERT Maths Class 8

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## Question

In a stack there are $$5$$ books each of thickness $$20\, \rm{mm}$$ and $$5$$ paper sheets each of thickness $$0.016\,\rm{mm}$$.

What is the total thickness of the stack?

Video Solution
Exponents And Powers
Ex 12.2 | Question 4

## Text Solution

What is known?

$$5$$ books of $$20\rm{mm}$$ thickness each. $$5$$ paper sheets of $$0.016\rm{mm}$$ thickness each.

What is unknown?

Total thickness of the stack

Reasoning:

First find the total thickness of $$5$$ books then find out total thickness of $$5$$ paper sheets. Now find total thickness of stack by adding these two.

Steps:

Thickness of each book $$= 20 \,\rm{mm}$$

Number of books per stack $$= 5$$

Thickness of $$5$$ books $$=5\times20=10\,\rm{mm}$$

Thickness of each sheet$$=0.016\,\rm{mm}$$

Thickness of 5 paper sheets

$$=5\times 0.016=0.080\,\,\text{mm}$$

Total thickness of stack

\begin{align} &= 100 +0.080 \\ & =100.080\;\rm{mm}\\ & =100.080 \\ & =1.0008\times10^2\,\rm{mm} \end{align}

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