在PHP中计算一个数字的平方根至少一个小数位[关闭]

I need to calculate the square root of a number to at least one decimal place without using the built-in PHP mathematical functions. In other words, we can only use multiplication, division, addition and subtraction.

Example: calculate_square_root(56) would result in: 7.4

Note: I need a recursion based code for above problem

Please help anyone to sort out the problem and thanks in advance.

Simple.....

function calculate_square_root($number) {
  return parseInt($number^0.5*10)/10;
}

edit sorry: here you go without built in...

edit2 as pointed out in the comments below, the caret ^ is not for power/exponent, but is for XOR. So This answer is WRONG.