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The product of 722*227 (163,894) contains neither 2 nor 7.
List all the couples (b,c; b>c) such that the product bcc*ccb contains neither b nor c.
Bonus: From the above list select couples, if any, using none of the corresponding digits in the partial products as well.
Suppose a and b are positive integers. We all know that aČ+2ab+bČ is a perfect square. Give an example where also aČ+ab+bČ is a perfect square. How many such examples exist?
Latest: 
Bonus: 
