Alright, let's work through 1787 times 3607 step by step
1787 × 3607 = 3607 × (1787)
+ 3607 × 7 resulting in 25249
+ 3607 × 80 that results in 288560
+ 3607 × 700 resulting in 2524900
+ 3607 × 1000 which equals 3607000

= 6445709
