What is X in the sequence 4, 196, 16, 144, 36, 100, 64, X

• Non Verbal Reasoning

What is X in the sequence 4, 196, 16, 144, 36, 100, 64, X?

1. 48
2. 64
3. 125
4. 256

Answer

On seeing the numbers, they are squares of numbers.

4 = 2²

196 = 14²

16 = 4²

144 = 12²

36 = 6²

100 = 10²

64 = 8²

The squares are alternatively increasing and decreasing by 2.

So, X = 8²

X = 64.

The correct option is B.