Question 40

Select the number from among the given options that can replace the question mark (?) in the following series.

13, 51, 205, 819, 3277, ?

Solution

$$13\times4-1 = 52-1 = 51$$

$$51\times4+1 = 204+1 = 205$$

$$205\times4-1 = 820-1 = 819$$

$$819\times4+1 = 3276+1 = 3277$$

$$3277\times4-1 = 13108-1 = 13107$$

So '13107' will come in place of the question mark.

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