Alright, let's work through 3966 times 5317 step by step
3966 × 5317 = 5317 × (3966)
+ 5317 × 6 which equals 31902
+ 5317 × 60 that equals 319020
+ 5317 × 900 that equals 4785300
+ 5317 × 3000 resulting in 15951000

= 21087222
