Alright, let's work through 8158 times 1715 step by step
8158 × 1715 = 1715 × (8158)
+ 1715 × 8 yielding 13720
+ 1715 × 50 what gives us 85750
+ 1715 × 100 which equals 171500
+ 1715 × 8000 what gives us 13720000

= 13990970
