Alright, let's work through 5245 times 644 step by step
5245 × 644 = 644 × (5245)
+ 644 × 5 resulting in 3220
+ 644 × 40 which equals 25760
+ 644 × 200 resulting in 128800
+ 644 × 5000 that equals 3220000

= 3377780
