Alright, let's work through 78400429 times 19639674 step by step
78400429 × 19639674 = 19639674 × (78400429)
+ 19639674 × 9 what gives us 176757066
+ 19639674 × 20 giving us 392793480
+ 19639674 × 400 that is equal 7855869600
+ 19639674 × 0000 what gives us 0
+ 19639674 × 00000 what gives us 0
+ 19639674 × 400000 that is equal 7855869600000
+ 19639674 × 8000000 what gives us 157117392000000
+ 19639674 × 70000000 which equals 1374777180000000

= 1539758867020146
