count
Level
1
Find the last digit of 1x2x3x4...........x99
The answer is 0.
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1 solution
1x2x3 x........ x 99 = 5! x 6 x 7 x ....... x 99 = 120 x 6 x 7 x ...... x 99 Every factor from 6 on will be multiplied by a multiple of 10 and so will have a product ending in 0.