Alright, let's work through 78398855 times 25734699 step by step
78398855 × 25734699 = 25734699 × (78398855)
+ 25734699 × 5 resulting in 128673495
+ 25734699 × 50 that is equal 1286734950
+ 25734699 × 800 yielding 20587759200
+ 25734699 × 8000 resulting in 205877592000
+ 25734699 × 90000 which equals 2316122910000
+ 25734699 × 300000 that is equal 7720409700000
+ 25734699 × 8000000 that results in 205877592000000
+ 25734699 × 70000000 producing 1801428930000000

= 2017570935369645
