# b - positive number to find square root
# x0 - start approximate root value
b = 64
x0 = 10

def foo(xn,a)
  xn = 0.5*(xn+a/xn)

  if xn**2 == a
  	return xn
  else
  	xn = foo(xn,a)
  end
end

puts foo(x0,b)