Math problem (simple but hard)

[sheetsworld]

Using the numbers 2, 4, 4, 6, and 6, make the number 55.

RULES

1) You can multiply, divide, add, subtract, square, square root. However, in order to square root a number, you need a 2. Likewise, to cube root a number, you need a 3.

2) You can only use each number once, and cannot do something to the zero power unless you have previously gotten a zero with other numbers.

3) Also, you cannot combine numbers into bigger numbers. (Example (44+66) /2.) Otherwise, you can do anything.