Alright, let's work through 1616 times 6445 step by step
1616 × 6445 = 6445 × (1616)
+ 6445 × 6 that results in 38670
+ 6445 × 10 that equals 64450
+ 6445 × 600 which equals 3867000
+ 6445 × 1000 what gives us 6445000

= 10415120
