Alright, let's work through 81039860 times 77658603 step by step
81039860 × 77658603 = 77658603 × (81039860)
+ 77658603 × 0 producing 0
+ 77658603 × 60 that equals 4659516180
+ 77658603 × 800 producing 62126882400
+ 77658603 × 9000 which equals 698927427000
+ 77658603 × 30000 resulting in 2329758090000
+ 77658603 × 000000 that is equal 0
+ 77658603 × 1000000 what gives us 77658603000000
+ 77658603 × 80000000 that results in 6212688240000000

= 6293442314915580
