Only ultra genius can solve it
The correct answer is 1260. Number 12 is derived as 4*2+4, first number 4 is derived 2*1+2, second number 4 is derived as 1*3+1, number 60 is derived as 12*4+12, number 20 is derived as 4*4+4, finally number 1260 is derived as 60*20+60 = 1260.
