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4.5, 4.5, 12.5, What?

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

 

Puzzle ID:#28194
Fun:*** (2.65)
Difficulty:*** (2.92)
Category:Series
Submitted By:thepianistalex*us***

 

 

 



A teacher got mad at a student, and gave him one last chance to see if he was paying attention. "You'll give me a number and I'll give you one back, and you must find out the rule. You only get five numbers! Once you get one wrong, you will get detention immediately!"

Here is a summary of what the student said and how the teacher replied.

Input 1 , 2 , 3 , 4, 5
Output 4.5, 4.5, 12.5, 8, 8

What is the rule?



Answer

The rule is to count the number of letters of the number, square it, then divide by two. So:

1 = 3
2 = 3
3 = 5
4 = 4
5 = 4

(3^2)/2 = 9/2 = 4.5
(3^2)/2 = 9/2 = 4.5
(5^2)/2 = 25/2 = 12.5
(4^2)/2 = 16/2 = 8
(4^2)/2 = 16/2 = 8

Luckily, that student didn't get detention because of his quick wit, but who knows if he will be lucky next time...

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