Alright, let's work through 81831721 times 73138231 step by step
81831721 × 73138231 = 73138231 × (81831721)
+ 73138231 × 1 that equals 73138231
+ 73138231 × 20 producing 1462764620
+ 73138231 × 700 giving us 51196761700
+ 73138231 × 1000 which equals 73138231000
+ 73138231 × 30000 giving us 2194146930000
+ 73138231 × 800000 that is equal 58510584800000
+ 73138231 × 1000000 that equals 73138231000000
+ 73138231 × 80000000 yielding 5851058480000000

= 5985027313625551
