HMMT-Feb 2010 guts, Problem 1

If $A=10^{9}-987654321$ and $B=\frac{123456789+1}{10}$, what is the value of $\sqrt{A B}$ ?

Solution: Both $A$ and $B$ equal 12345679 , so $\sqrt{A B}=12345679$ as well. $\fbox{12345679}$.

Answer: 12345679