Did you get it right?
This number sequence asks you to find the next number after 4, 9, 19, and 39.
The Answer
The correct answer is: 79.
Here is why
- Each number is doubled, then 1 is added.
- 4 x 2 + 1 = 9.
- 9 x 2 + 1 = 19.
- 19 x 2 + 1 = 39.
- 39 x 2 + 1 = 79.
Why people miss it
The differences keep growing, so the pattern looks random until you test doubling plus one.
What answer did you get before checking?
