Alright, let's work through 80210101 times 54789257 step by step
80210101 × 54789257 = 54789257 × (80210101)
+ 54789257 × 1 giving us 54789257
+ 54789257 × 00 yielding 0
+ 54789257 × 100 resulting in 5478925700
+ 54789257 × 0000 resulting in 0
+ 54789257 × 10000 that equals 547892570000
+ 54789257 × 200000 giving us 10957851400000
+ 54789257 × 0000000 giving us 0
+ 54789257 × 80000000 which equals 4383140560000000

= 4394651837684957
