Alright, let's work through 1660 times 860 step by step
1660 × 860 = 860 × (1660)
+ 860 × 0 what gives us 0
+ 860 × 60 that equals 51600
+ 860 × 600 resulting in 516000
+ 860 × 1000 giving us 860000

= 1427600
