# square root and cube root aptitude questions

1. The cube root of .000216 is:
 A. 0.6 B. 0.06 C. 77 D. 87

Explanation:

 (.000216)1/3 = 216 1/3 106

 = 6 x 6 x 6 1/3 102 x 102 x 102

 = 6 102

 = 6 100

= 0.06

2.

 What should come in place of both x in the equation x = 162 . 128 x
 A. 12 B. 14 C. 144 D. 196

Explanation:

 Let x = 162 128 x

Then x2 = 128 x 162

= 64 x 2 x 18 x 9

= 82 x 62 x 32

= 8 x 6 x 3

= 144.

x = 144 = 12.

3. The least perfect square, which is divisible by each of 21, 36 and 66 is:
 A. 213444 B. 214344 C. 214434 D. 231444

Explanation:

L.C.M. of 21, 36, 66 = 2772.

Now, 2772 = 2 x 2 x 3 x 3 x 7 x 11

To make it a perfect square, it must be multiplied by 7 x 11.

So, required number = 22 x 32 x 72 x 112 = 213444

4. 1.5625 = ?
 A. 1.05 B. 1.25 C. 1.45 D. 1.55

Explanation:

```   1|1.5625( 1.25
|1
|-------
22| 56
| 44
|-------
245| 1225
| 1225
|-------
|    X
|-------```

1.5625 = 1.25.

5.

If 35 + 125 = 17.88, then what will be the value of 80 + 65 ?

 A. 13.41 B. 20.46 C. 21.66 D. 22.35

Explanation:

35 + 125 = 17.88

35 + 25 x 5 = 17.88

35 + 55 = 17.88

85 = 17.88

5 = 2.235

80 + 65 = 16 x 5 + 65

= 45 + 65

= 105 = (10 x 2.235) = 22.35