Question

Find the number missing at question mark: 10, 11, 23, 39, 64, ?, 149

Answer 1

I think the missing number should be 105.

Let we find the common difference of 10, 11, 23, 39, 64.
i.e. 1, 12, 16, 25
Differences of 1, 12, 16, 25 is 11, 4, 9.
Again, the difference is 7, 5 and finally 2.

So, 2 + 5 + 9 + 25 = 41
Then, 64 + 41 = 105.

Therefore, the series is 10, 11, 23, 39, 64, 105, 149.

Answer 2

The number missing at question mark is 100

Given,

The sequence of numbers 10, 11, 23, 39, 64, ?, 149

To Find,

The number missing at '?'

Solution,

The differences between the numbers 10, 14, 23, 39, and 64 are 4, 9, 16, and 25

that is, the differences are 2*2, 3*3, 4*4, and 5*5

Therefore, the difference between 64 and the next number, say x, is 6*6 = 36

⇒ x-64 =  36

⇒ x = 64 +  36

⇒ x =  100

To check this, we take the difference between 100 and 149 = 49 = 7*7

Therefore, the required answer is 100

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