We're going to solve 7821 multiplied by 1005
7821 × 1005 = 1005 × (7821)
+ 1005 × 1 that is equal 1005
+ 1005 × 20 that is equal 20100
+ 1005 × 800 that results in 804000
+ 1005 × 7000 producing 7035000

= 7860105
