Question

Using square root table, find the square root

Answer 1

We have to find $\sqrt{21.97}$.
From the square root table, we have:
$\sqrt{21}=\sqrt{3}\times \sqrt{7}=4.583\mathrm{and}\sqrt{22}=\sqrt{2}\times \sqrt{11}$=4.690
Their difference is 0.107.
Thus, for the difference of 1 (22 $-$ 21), the difference in the values of the square roots is 0.107.
For the difference of 0.97, the difference in the values of their square roots is:
$0.107\times 0.97=0.104$
$\therefore$ $\sqrt{21.97}=4.583+0.104\approx 4.687$