What is the next number in the series: 2, 3, 5, 8, 12, 17, _?

To find the next number in the series 2, 3, 5, 8, 12, 17, we first examine the differences between consecutive numbers:

• 3 - 2 = 1

• 5 - 3 = 2

• 8 - 5 = 3

• 12 - 8 = 4

• 17 - 12 = 5

The differences are: 1, 2, 3, 4, 5. As we can see, the differences themselves are increasing by 1 each time. To find the next number in the series, we continue this pattern in the differences. The next difference after 5 would be 6.

Adding this difference to the last number in the series:

17 + 6 = 23.

Therefore, the next number in the series is 23.