Alright, let's work through 3905 times 8164 step by step
3905 × 8164 = 8164 × (3905)
+ 8164 × 5 that is equal 40820
+ 8164 × 00 giving us 0
+ 8164 × 900 that is equal 7347600
+ 8164 × 3000 yielding 24492000

= 31880420
