Question

The least number which must be subtracted from 6,156 to make it a perfect square is:

• A. 62
• B. 72
• C. 52
• D. 82

Answer 1

The correct option is B 72

First we will find the square root of $6156$:

$\sqrt{6156}=\sqrt{2\times 2\times 3\times 3\times 3\times 3\times 19}=2\times 3\times 3\times \sqrt{19}=18\times 4.358=\mathrm{78.444...}$

Now, we find the square of $78$ as follows:

${78}^2=78\times 78=6084$

Let us now subtract $6156$ from $6084$ as shown below:

$6156-6084=72$

Hence, $72$ will be subtracted from $6156$ to make it a perfect square.