Alright, let's work through 81651009 times 99812010 step by step
81651009 × 99812010 = 99812010 × (81651009)
+ 99812010 × 9 what gives us 898308090
+ 99812010 × 00 yielding 0
+ 99812010 × 000 yielding 0
+ 99812010 × 1000 which equals 99812010000
+ 99812010 × 50000 which equals 4990600500000
+ 99812010 × 600000 that equals 59887206000000
+ 99812010 × 1000000 what gives us 99812010000000
+ 99812010 × 80000000 that equals 7984960800000000

= 8149751326818090
