Optimized version of `primes less than n` written in Go

primes_faster.go

package main

import (
    "fmt";
    "os";
    "strconv";
    "log";
    "math";
)

func IsPrime(target int) bool {
    isPrime := true;
    if target > 2 {
        for num := 2; num < target; num++ {
            if target % num == 0 {
                isPrime = false
                break
            }
        }
    }
    return isPrime
}

func FastIsPrime(target int) bool {
    /* Only check against numbers less than the square root of our target plus one. */
    isPrime := true;
    if target > 2 {
        for num := 2; num < int(math.Sqrt(float64(target))) + 1; num++ {
            if target % num == 0 {
                isPrime = false
                break
            }
        }
    }
    return isPrime
}

func GetPrimesLessThan(target int) {
    numFound := 0
    for num := 2; num <= target; num++ {
        if FastIsPrime(num) {
            numFound++
            // fmt.Printf("%v\n", num)
        }
    }
    fmt.Printf("Found %v primes below %v.\n",numFound, target)
}

func main() {
    args := os.Args
    target, err := strconv.Atoi(args[1])
    if err != nil {
        log.Fatal(err)

    }
    GetPrimesLessThan(target)
}