Question 218355
To have  a  product  of  Zero,,one  of  the  numbers  MUST  be  Zero.
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As  this  is  excluded  ,,,answer  is  NEVER.
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for  example,,,,1 * -1 =-1.....or  2*-2 = -4,,,,etc
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This  sounds  like  the  true  statement,,,the  SUM  of  a  number  and  its  opposite  is  Zero.
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for  example,,,,(1) +(-1) =0,,,,,or (2) +(-2)=0
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