Alright, let's work through 9940 times 6428 step by step
9940 × 6428 = 6428 × (9940)
+ 6428 × 0 yielding 0
+ 6428 × 40 that is equal 257120
+ 6428 × 900 giving us 5785200
+ 6428 × 9000 that equals 57852000

= 63894320
