My solution to the loops and functions exercise http://tour.golang.org/#24

loops.go

package main

import (
    "fmt"
    "math"
)

func Sqrt(x float64) float64 {
    next := float64(1)
    prev := float64(0)
    for math.Abs(next - prev) > .01 {
        prev, next = next, next - (next*next - x)/(2*next)
    }
    return next
}

func main() {
    fmt.Println(Sqrt(2))
}