Alright, let's work through 9143 times 9640 step by step
9143 × 9640 = 9640 × (9143)
+ 9640 × 3 what gives us 28920
+ 9640 × 40 that is equal 385600
+ 9640 × 100 giving us 964000
+ 9640 × 9000 that is equal 86760000

= 88138520
