Alright, let's work through 85105739 times 78031203 step by step
85105739 × 78031203 = 78031203 × (85105739)
+ 78031203 × 9 yielding 702280827
+ 78031203 × 30 that results in 2340936090
+ 78031203 × 700 that is equal 54621842100
+ 78031203 × 5000 producing 390156015000
+ 78031203 × 00000 that results in 0
+ 78031203 × 100000 producing 7803120300000
+ 78031203 × 5000000 producing 390156015000000
+ 78031203 × 80000000 that equals 6242496240000000

= 6640903196374017
