Number Puzzle #161

If

2-1=3

4-4=0

8-5=40

10-10=???

Check your answer:-

here a-b=axa+(a/2)x(a/2)-axb

2-1=2×2+(2/2)x(2/2)-2×1=3

8-5=8×8+(8/2)x(8/2)-8×5=40

4-4=4×4+(4/2)x(4/2)-4×4=4

thus

10-10=10×10+(10/2)x(10/2)-10×10=25