Alright, let's work through 99830380 times 47990721 step by step
99830380 × 47990721 = 47990721 × (99830380)
+ 47990721 × 0 giving us 0
+ 47990721 × 80 resulting in 3839257680
+ 47990721 × 300 that equals 14397216300
+ 47990721 × 0000 that equals 0
+ 47990721 × 30000 that is equal 1439721630000
+ 47990721 × 800000 that is equal 38392576800000
+ 47990721 × 9000000 that results in 431916489000000
+ 47990721 × 90000000 that results in 4319164890000000

= 4790931913903980
