# [Golang] – Code example to calc roots

To calc the root we will use here the Newton Raphson Method. In this case, Newton’s formula is to approximate Sqrt(x) by picking a guess starting point z and then repeating it: z – (z*z-x)/(2*z). To understand it mathematically check the following video.

Following my solution in Golang.

```package main

import (
"fmt"
)

func Sqrt(x float64) float64 {
z := 1.0 // initial guess to be 1
i := 0
for int(z*z) != int(x) { // until find the first approximation
// Newton root algorithm
z -= (z*z - x) / (2 * z)
i++
}
return z
}

func main() {
fmt.Println(Sqrt(8900009870))
}```

Following a classic/common solution.

```package main

import (
"fmt"
"math"
)

func Sqrt(num float64) float64 {
const DIFF = 0.0001 // To fix the precision
z := 1.0

for {
z1 := z - (((z * z) - num) / (2 * z))
// Return a result when the diff between the last execution
// and the current one is lass than the precision constant
if (math.Abs(z1 - z) < DIFF) {
break
}
z = z1
}

return z
}

func main() {
fmt.Println(Sqrt(94339))
}```