Alright, let's work through 71906720 times 64389121 step by step
71906720 × 64389121 = 64389121 × (71906720)
+ 64389121 × 0 what gives us 0
+ 64389121 × 20 resulting in 1287782420
+ 64389121 × 700 producing 45072384700
+ 64389121 × 6000 that results in 386334726000
+ 64389121 × 00000 that results in 0
+ 64389121 × 900000 yielding 57950208900000
+ 64389121 × 1000000 producing 64389121000000
+ 64389121 × 70000000 that equals 4507238470000000

= 4630010494793120
