Golang Monte Carlo Pi

package main

import (
    "fmt"
    "math"
    "math/rand"
    "time"
)

const SAMPLES uint64 = 1000000000

func main() {

    startTime := time.Now()

    seed := rand.NewSource(time.Now().UnixNano())
    r := rand.New(seed)
    pointsInside := 0
    var mpi float64
    var x, y float64

    var i uint64
    for i = 0; i < SAMPLES; i++ {
        x, y = r.Float64(), r.Float64()

        //p = a^2 + b^2 = c^2
        //sqrt not necessary because checking for p^2 > 1 is the same as p > 1
        p2 := x*x + y*y

        //check if inside quartercircle
        if p2 < 1 {
            pointsInside++
        }
        mpi = float64(pointsInside*4) / float64(i)

        //Print current result every 10000000 samples
        if i > 0 && (i%100000000 == 0) {
            fmt.Printf("\nMontecarlo Pi with %v Samples: %v"+
                "\nCurrent Error: %v\n", i, mpi, math.Abs(math.Pi-mpi))
        }
    }

    //Final Conclusion
    mpi = float64(pointsInside*4) / float64(SAMPLES)
    fmt.Println("\nPoints inside quarter circle:", pointsInside, "of", SAMPLES)
    fmt.Println("Montecarlo Pi with", SAMPLES, "Samples:", mpi)
    fmt.Println("real Pi:", math.Pi)
    fmt.Println("Error:", math.Abs(math.Pi-mpi))
    fmt.Println("Time:", time.Now().Sub(startTime))
}