Alright, let's work through 1983 times 421 step by step
1983 × 421 = 421 × (1983)
+ 421 × 3 that is equal 1263
+ 421 × 80 what gives us 33680
+ 421 × 900 that equals 378900
+ 421 × 1000 which equals 421000

= 834843
