Alright, let's work through 1639 times 3487 step by step
1639 × 3487 = 3487 × (1639)
+ 3487 × 9 which equals 31383
+ 3487 × 30 what gives us 104610
+ 3487 × 600 that equals 2092200
+ 3487 × 1000 producing 3487000

= 5715193
