Matthew's favourite number is 47.

Jacob's favourite number is 17.

Tony's favourite number is 38.

What is Evan's favourite number?

22

Because

Taking the position of every letter in the alphabet and adding the length, dividing by two and then subtracting 1 from the result gives the numbers for each name.

Example

Matthew $\rightarrow \lfloor\frac{13+1+20+20+8 + 5 + 23 + 7}{2}\rfloor-1 = \lfloor 97/2 \rfloor -1 = 47$

• You mean $\dfrac{a+b+...+z}{2} + 1$? – manshu Jan 29 '16 at 18:57
• Good job! That is the correct answer! I got the numbers a different way though this way gives the same numbers. – GamrCorps Jan 29 '16 at 19:25
• Out of curiosity, @GamrCorps, how did you get the numbers? – tinezekis Jan 29 '16 at 22:17
• @caonayemi I took the alphabet and mapped it to its number in the alphabet (A=1, B=2, etc.) then divided each number by 2 and took the ceiling (result was A=1, B=1, C=2, D=2, etc.), then I just added all of the numbers in the persons name. – GamrCorps Jan 29 '16 at 22:44