Question 765931
Find the smallest number that both 
20 and 30 divide into evenly
{{{ 120 / 20 = 6 }}}
{{{ 120 / 30 = 4 }}}
but,
{{{ 60/20 = 3 }}}
{{{ 60/30 = 2 }}}
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In 60 seconds, or 8:01 PM, they both 
flash together