Alright, let's work through 87512320 times 91664919 step by step
87512320 × 91664919 = 91664919 × (87512320)
+ 91664919 × 0 that results in 0
+ 91664919 × 20 what gives us 1833298380
+ 91664919 × 300 that is equal 27499475700
+ 91664919 × 2000 that is equal 183329838000
+ 91664919 × 10000 that equals 916649190000
+ 91664919 × 500000 which equals 45832459500000
+ 91664919 × 7000000 yielding 641654433000000
+ 91664919 × 80000000 resulting in 7333193520000000

= 8021809724302080
