Alright, let's work through 78780056 times 19864355 step by step
78780056 × 19864355 = 19864355 × (78780056)
+ 19864355 × 6 resulting in 119186130
+ 19864355 × 50 that equals 993217750
+ 19864355 × 000 resulting in 0
+ 19864355 × 0000 yielding 0
+ 19864355 × 80000 that is equal 1589148400000
+ 19864355 × 700000 that equals 13905048500000
+ 19864355 × 8000000 that results in 158914840000000
+ 19864355 × 70000000 giving us 1390504850000000

= 1564914999303880
