Alright, let's work through 40512021 times 99915065 step by step
40512021 × 99915065 = 99915065 × (40512021)
+ 99915065 × 1 resulting in 99915065
+ 99915065 × 20 which equals 1998301300
+ 99915065 × 000 what gives us 0
+ 99915065 × 2000 resulting in 199830130000
+ 99915065 × 10000 producing 999150650000
+ 99915065 × 500000 producing 49957532500000
+ 99915065 × 0000000 yielding 0
+ 99915065 × 40000000 yielding 3996602600000000

= 4047761211496365
