Alright, let's work through 80309009 times 85207890 step by step
80309009 × 85207890 = 85207890 × (80309009)
+ 85207890 × 9 giving us 766871010
+ 85207890 × 00 producing 0
+ 85207890 × 000 resulting in 0
+ 85207890 × 9000 that equals 766871010000
+ 85207890 × 00000 that is equal 0
+ 85207890 × 300000 that results in 25562367000000
+ 85207890 × 0000000 resulting in 0
+ 85207890 × 80000000 yielding 6816631200000000

= 6842961204881010
