Alright, let's work through 78136538 times 87386547 step by step
78136538 × 87386547 = 87386547 × (78136538)
+ 87386547 × 8 producing 699092376
+ 87386547 × 30 that equals 2621596410
+ 87386547 × 500 that results in 43693273500
+ 87386547 × 6000 resulting in 524319282000
+ 87386547 × 30000 what gives us 2621596410000
+ 87386547 × 100000 which equals 8738654700000
+ 87386547 × 8000000 that is equal 699092376000000
+ 87386547 × 70000000 producing 6117058290000000

= 6828082250354286
