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Age 11 to 14
Challenge Level

Answer: No, but we know that your number ends in a 9 (one of 19, 29, 39, ...)



If the number is written $ab$, then the number is $10a+b$

$a\times b + (a+b) = 10a + b \Rightarrow ab + a = 10a$

$ab + a = (b+1)a$ so $b+1=10\Rightarrow b=9$ (or $a=0$)

But then $a$ could be anything!