Alright, let's work through 5399 times 644 step by step
5399 × 644 = 644 × (5399)
+ 644 × 9 giving us 5796
+ 644 × 90 that equals 57960
+ 644 × 300 that equals 193200
+ 644 × 5000 that results in 3220000

= 3476956
