Alright, let's work through 1801 times 3571 step by step
1801 × 3571 = 3571 × (1801)
+ 3571 × 1 that equals 3571
+ 3571 × 00 giving us 0
+ 3571 × 800 that equals 2856800
+ 3571 × 1000 that equals 3571000

= 6431371
