Calculation steps:169 (1/2) =13.

The difference between square root and arithmetic square root is that the square root can be positive, negative or 0, but the arithmetic square root must be non-negative.

Square story

Legend has it that a foreign minister in India played chess with the king. The king lost and promised to meet his demand: put the rice on the chessboard. Put 1 capsule in the first box, 2 capsules in the second box, then 4 capsules, 8 capsules, 16 capsules ... until 64 capsules are put in. The king smiled and thought that he was stupid and that it was only a little bit of rice.