Alright, let's work through 6468 times 6668 step by step
6468 × 6668 = 6668 × (6468)
+ 6668 × 8 what gives us 53344
+ 6668 × 60 that results in 400080
+ 6668 × 400 that is equal 2667200
+ 6668 × 6000 yielding 40008000

= 43128624
