Alright, let's work through 25815664 times 42123542 step by step
25815664 × 42123542 = 42123542 × (25815664)
+ 42123542 × 4 that results in 168494168
+ 42123542 × 60 that results in 2527412520
+ 42123542 × 600 what gives us 25274125200
+ 42123542 × 5000 which equals 210617710000
+ 42123542 × 10000 that equals 421235420000
+ 42123542 × 800000 that is equal 33698833600000
+ 42123542 × 5000000 giving us 210617710000000
+ 42123542 × 20000000 producing 842470840000000

= 1087447206761888
