Question

Substract 2.5 x 10 from 4.0 x 10 with due re- gard to significant figures.​

Answer 1

As no power given I have taken power of 10 as n

Lets substract

$\\ \sf\longmapsto 4.0\times 10^n- 2.5\times 10^n$

$\\ \sf\longmapsto (4.0-2.5)10^n$

$\\ \sf\longmapsto 1.5\times 10^n$

• As per rule zeros to right are not counted along significant figures.Hence Number of significant figures are 2.

Answer 2

As no power given I have taken power of 10 as n

Lets subtract ,

$\begin{gathered}\\ \sf\longmapsto 4.0\times 10^n- 2.5\times 10^n\end{gathered} \\ \\ \begin{gathered}\\ \sf\longmapsto (4.0-2.5)10^n\end{gathered} \\ \\ \begin{gathered}\\ \sf\longmapsto 1.5\times 10^n\end{gathered}$

• As per rule zeros to right are not counted along significant figures.Hence Number of significant figures are 2.