Alright, let's work through 15758954 times 78420271 step by step
15758954 × 78420271 = 78420271 × (15758954)
+ 78420271 × 4 resulting in 313681084
+ 78420271 × 50 that results in 3921013550
+ 78420271 × 900 what gives us 70578243900
+ 78420271 × 8000 resulting in 627362168000
+ 78420271 × 50000 producing 3921013550000
+ 78420271 × 700000 that equals 54894189700000
+ 78420271 × 5000000 giving us 392101355000000
+ 78420271 × 10000000 producing 784202710000000

= 1235821443356534
