Question 1027590
Adding 25 tiles is:
12 tiles along one side
12 tiles along the other side
1 tile in the corner
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That means there was a {{{ 12*12 = 144 }}}
square before adding 25 tiles
{{{ 144 + 25 = 169 }}}
{{{ sqrt( 169 ) = 13 }}}
So, the size of the floor is 13 x 13 tiles