GCD in go

gcd.go

package main

import (
	"fmt"
	"math"
)

func gcd(a, b int) int {
	for b != 0 {
		rem := math.Mod(float64(a), float64(b))
		a = b
		b = int(rem)
	}

	return a
}

func main() {
	fmt.Println(gcd(30, 8))
}

Why math.Mod and conversion between int and float64 when there's % ?

func gcd(a, b int) int {
    for b > 0 {
        a, b = b, a%b
    }

    return a
}