Theory:

ii) Division of a decimal number by a whole number
Let us learn how to divide the decimal number by a whole number.

i) $$8.4 ÷ 2$$

$$8.4 ÷ 2 =$$ $\frac{8.4}{2}=8.4×\frac{1}{2}$. We can write $$8.4$$ as $\frac{84}{10}$.

So, $\frac{84}{10}×\frac{1}{2}=\frac{{\overline{)84}}^{42}}{10}×\frac{1}{\overline{)2}}=\frac{42}{10}=4.2$

Therefore, $\frac{8.4}{2}=4.2$.

In another way, we can divide given expression using the normal division method.

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iii) Division of a decimal number by another decimal number:
i) Find the value of $$30.8 ÷ 0.7$$.

The given expression $\frac{30.8}{0.7}$. We can rewrite it as $\frac{\frac{308}{10}}{\frac{7}{10}}=\frac{308}{10}×\frac{10}{7}$.

Let us simplify it.

$\frac{308}{\overline{)10}}×\frac{\overline{)10}}{7}=\frac{308}{7}=44$

Therefore, the value of $$30.8 ÷ 0.7$$ is $$44$$.

ii) Find the value of $$115.2 ÷ 0.9$$.

Similarly, we can rewrite the given expression $\frac{115.2}{0.9}$ as $\frac{\frac{1152}{10}}{\frac{9}{10}}=\frac{1152}{10}×\frac{10}{9}$.

$$=$$ $\frac{1152}{\overline{)10}}×\frac{\overline{)10}}{9}=\frac{1152}{9}=128$.

Therefore, $$115.2 ÷ 0.9 = 128$$.