To get the best estimate of the square root of 90 we will apply a short cut.
Square root of 90 will be in the form of a mixed fraction as
or in decimals.
Here, a = square root of a perfect square number nearest to 90.
b = Difference of 90 and the perfect square number
c = Double of 'a'
Nearest square number to 90 = 81
Square root of 81 = 9
So, a = 9
Difference in 90 and 81 = 9
So, b = 90 - 81 = 9
And double of 9 = 18
Therefore, c = 18
Hence, ![\sqrt{90}\approx9\frac{9}{18}](/tpl/images/0790/5368/b43f7.png)
![\approx9.5](/tpl/images/0790/5368/2f069.png)
So the nearest number given in the option may be 9.4
Therefore, Option B will be the answer.
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