Which number is next?
Level
1
12, 15, 21, 24, 30, 33, 39, 51, _ _
The answer is 57.
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1 solution
Start with the first value. Add the sum of that value's digits to the number to obtain the next value. So, 12 + (1+2) = 15
15 + (1+5) = 21 Continue in the same manner. The value after 51 would then be 51 + (5+1) = 57