Alright, let's work through 39967987 times 28904733 step by step
39967987 × 28904733 = 28904733 × (39967987)
+ 28904733 × 7 yielding 202333131
+ 28904733 × 80 producing 2312378640
+ 28904733 × 900 yielding 26014259700
+ 28904733 × 7000 what gives us 202333131000
+ 28904733 × 60000 that equals 1734283980000
+ 28904733 × 900000 yielding 26014259700000
+ 28904733 × 9000000 resulting in 260142597000000
+ 28904733 × 30000000 what gives us 867141990000000

= 1155263992782471
