Alright, let's work through 90838399 times 42158207 step by step
90838399 × 42158207 = 42158207 × (90838399)
+ 42158207 × 9 producing 379423863
+ 42158207 × 90 that equals 3794238630
+ 42158207 × 300 what gives us 12647462100
+ 42158207 × 8000 that results in 337265656000
+ 42158207 × 30000 which equals 1264746210000
+ 42158207 × 800000 giving us 33726565600000
+ 42158207 × 0000000 yielding 0
+ 42158207 × 90000000 which equals 3794238630000000

= 3829584028590593
