### Brain Teasers

# 1, 5, 9, 15, ?

Series
Series teasers are where you try to complete the sequence of a series of letters, numbers or objects.

What is the next number in the sequence:

1, 5, 9, 15, ?

1, 5, 9, 15, ?

### Answer

The numbers represent the position in the alphabet of the letters a, e, i, and o which are the first four vowels. The next number in the sequence is therefore 21 which represents the letter u.Hide Answer Show Answer

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