Alright, let's work through 20900504 times 87770729 step by step
20900504 × 87770729 = 87770729 × (20900504)
+ 87770729 × 4 what gives us 351082916
+ 87770729 × 00 that is equal 0
+ 87770729 × 500 that is equal 43885364500
+ 87770729 × 0000 that equals 0
+ 87770729 × 00000 which equals 0
+ 87770729 × 900000 producing 78993656100000
+ 87770729 × 0000000 which equals 0
+ 87770729 × 20000000 yielding 1755414580000000

= 1834452472547416
