Question 1088969
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<U>Answer</U>. There are two consecutive numbers X and X+1 such that their product equal to Y &nbsp;&nbsp;<U>IF AND ONLY IF</U> 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the quadratic equation &nbsp;{{{X*(X+1)}}} = {{{Y}}} &nbsp;has a solution in integer numbers.