Alright, let's work through 12947849 times 81396429 step by step
12947849 × 81396429 = 81396429 × (12947849)
+ 81396429 × 9 which equals 732567861
+ 81396429 × 40 resulting in 3255857160
+ 81396429 × 800 producing 65117143200
+ 81396429 × 7000 that results in 569775003000
+ 81396429 × 40000 resulting in 3255857160000
+ 81396429 × 900000 resulting in 73256786100000
+ 81396429 × 2000000 yielding 162792858000000
+ 81396429 × 10000000 what gives us 813964290000000

= 1053908671831221
