Solve This

Pura Pagal

Member
May 2, 2008
1,233
29
0
15 + 13 = 28
28 + 17 = 45
45 + 21 = 66
66 + 25 = 91

91 is the hidden number......

From where did 13, 17, 21, and 25 came in (logic). According to my understanding this is within the number grid, that is why I asked if a solution is required!