Alright, let's work through 1390 times 8031 step by step
1390 × 8031 = 8031 × (1390)
+ 8031 × 0 that equals 0
+ 8031 × 90 what gives us 722790
+ 8031 × 300 yielding 2409300
+ 8031 × 1000 what gives us 8031000

= 11163090
