Find the lowest common multiple of 24, 36 and 40.

 2 | 24  -  36  - 40
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 2 | 12  -  18  - 20
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 2 |  6  -   9  - 10
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 3 |  3  -   9  -  5
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   |  1  -   3  -  5
   
L.C.M.  = 2 x 2 x 2 x 3 x 3 x 5 = 360.