Alright, let's work through 78389851 times 20206923 step by step
78389851 × 20206923 = 20206923 × (78389851)
+ 20206923 × 1 which equals 20206923
+ 20206923 × 50 that equals 1010346150
+ 20206923 × 800 yielding 16165538400
+ 20206923 × 9000 that is equal 181862307000
+ 20206923 × 80000 yielding 1616553840000
+ 20206923 × 300000 what gives us 6062076900000
+ 20206923 × 8000000 that is equal 161655384000000
+ 20206923 × 70000000 that is equal 1414484610000000

= 1584017683138473
