Alright, let's work through 88420797 times 91780507 step by step
88420797 × 91780507 = 91780507 × (88420797)
+ 91780507 × 7 what gives us 642463549
+ 91780507 × 90 giving us 8260245630
+ 91780507 × 700 that results in 64246354900
+ 91780507 × 0000 which equals 0
+ 91780507 × 20000 resulting in 1835610140000
+ 91780507 × 400000 which equals 36712202800000
+ 91780507 × 8000000 resulting in 734244056000000
+ 91780507 × 80000000 producing 7342440560000000

= 8115305578004079
