Alright, let's work through 3613 times 1387 step by step
3613 × 1387 = 1387 × (3613)
+ 1387 × 3 that results in 4161
+ 1387 × 10 that equals 13870
+ 1387 × 600 producing 832200
+ 1387 × 3000 resulting in 4161000

= 5011231
