Alright, let's work through 81990198 times 21305305 step by step
81990198 × 21305305 = 21305305 × (81990198)
+ 21305305 × 8 yielding 170442440
+ 21305305 × 90 that results in 1917477450
+ 21305305 × 100 resulting in 2130530500
+ 21305305 × 0000 giving us 0
+ 21305305 × 90000 that equals 1917477450000
+ 21305305 × 900000 resulting in 19174774500000
+ 21305305 × 1000000 that is equal 21305305000000
+ 21305305 × 80000000 what gives us 1704424400000000

= 1746826175400390
