# Ex.12.2 Q2 Exponents and Powers - NCERT Maths Class 8

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## Question

Express the following numbers in usual form.

(i) $$3.02 \times 10^{-6}$$

(ii) $$4.5 \times 10^{4}$$

(iii) \begin{align}\text{3 }\!\!\times\!\!\text{ 1}{{\text{0}}^{-8}}\end{align}

(iv) $$1.0001 \times 10^{9}$$

(v) $$5.8 \times 10^{12}$$

(vi) $$3.61492 \times 10^{6}$$

Video Solution
Exponents And Powers
Ex 12.2 | Question 2

## Text Solution

What is known?

Standard form

What is unknown?

Usual form

Reasoning:

As we know standard form of any small or larger number is $$a.b \times {10^n}$$,Where $$a$$ is a whole number, $$b$$ is a decimal number and $$n$$ is an integer

For small number $$n$$ is negative and for large number $$n$$ is positive. So, to convert a small number to its usual form we need to move decimal to its left by number of steps given as exponent values.

Steps:

(i) $$\,3.02 \times {10^{ - 6}}$$

$$\therefore$$ Its usual form is

\begin{align}3.02 \times {10^{ - 6}} &= \frac{{3.02}}{{1000000}}\\&= 0.00000302\end{align}

(ii) $$\,4.5 \times {10^4}$$

Now to convert a big number to its usual form we need to move decimal to its right by number of steps given as its exponent.

$4.5 \times {10^4}= 45000$

$$\therefore$$ Answer is $$45000$$

(iii) $$\,3 \times {10^{ - 8}} = {{ }}0.00000003$$

(iv) $$1.0001 \times {10^9} = 1000100000$$

(v) $$\,5.8 \times {10^{12}} = {{ }}5800000000000$$

(vi) $$\,3.61492 \times {10^6} = 3614920$$

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