multiplication pyramid

This is my multiplication pyramid. For this task we have to times two numbers of the pyramid and keep moving up until you get to the top.

working out for the third row numbers


________
75 x 405=
70 x 400 = 28000
70 x 5 =350
_
5 x 400 =2000
5 x 5 = 25
_
28000 + 350 + 2000 + 25 = 30375
____________________________

__________
405 x 486 =
400 x 400 =160000
400 x 80 =32000
400 x 6 = 2400
_
5 x 80 = 400
5 x 6 = 30
_
160000 + 32000 + 2400 + 400 + 30 = 194830

then I had permission from my maths teacher to calculate the top answers