Alright, let's work through 7610728 times 77091991 step by step
7610728 × 77091991 = 77091991 × (7610728)
+ 77091991 × 8 producing 616735928
+ 77091991 × 20 that equals 1541839820
+ 77091991 × 700 that equals 53964393700
+ 77091991 × 0000 which equals 0
+ 77091991 × 10000 resulting in 770919910000
+ 77091991 × 600000 resulting in 46255194600000
+ 77091991 × 7000000 giving us 539643937000000

= 586726174479448
