Alright, let's work through 5142 times 3957 step by step
5142 × 3957 = 3957 × (5142)
+ 3957 × 2 resulting in 7914
+ 3957 × 40 giving us 158280
+ 3957 × 100 producing 395700
+ 3957 × 5000 producing 19785000

= 20346894
