Alright, let's work through 67642893 times 8540309 step by step
67642893 × 8540309 = 8540309 × (67642893)
+ 8540309 × 3 that results in 25620927
+ 8540309 × 90 that equals 768627810
+ 8540309 × 800 resulting in 6832247200
+ 8540309 × 2000 resulting in 17080618000
+ 8540309 × 40000 yielding 341612360000
+ 8540309 × 600000 giving us 5124185400000
+ 8540309 × 7000000 that results in 59782163000000
+ 8540309 × 60000000 producing 512418540000000

= 577691207873937
