Alright, let's work through 83944845 times 12971245 step by step
83944845 × 12971245 = 12971245 × (83944845)
+ 12971245 × 5 which equals 64856225
+ 12971245 × 40 what gives us 518849800
+ 12971245 × 800 yielding 10376996000
+ 12971245 × 4000 resulting in 51884980000
+ 12971245 × 40000 that results in 518849800000
+ 12971245 × 900000 that results in 11674120500000
+ 12971245 × 3000000 giving us 38913735000000
+ 12971245 × 80000000 that equals 1037699600000000

= 1088869150982025
