Alright, let's work through 64061991 times 78303808 step by step
64061991 × 78303808 = 78303808 × (64061991)
+ 78303808 × 1 what gives us 78303808
+ 78303808 × 90 which equals 7047342720
+ 78303808 × 900 giving us 70473427200
+ 78303808 × 1000 giving us 78303808000
+ 78303808 × 60000 that results in 4698228480000
+ 78303808 × 000000 that is equal 0
+ 78303808 × 4000000 yielding 313215232000000
+ 78303808 × 60000000 which equals 4698228480000000

= 5016297843361728
