Go Array Calculate Standard Deviation

package main/*from   w w  w  .j a  v  a2 s .c o  m*/
import (
    "fmt"
    "math"
)
func main(){  
    var num[10] float64
    var sum,mean,sd float64
  
  for i := 1; i <= 10; i++ {
    num[i-1] = float64(i) + 123
    sum += num[i-1]
  }
  mean = sum/10;

  for j := 0; j < 10; j++ {
        sd += math.Pow(num[j] - mean, 2)
    }
    sd = math.Sqrt(sd/10)

    fmt.Println("The Standard Deviation is : ",sd)    
}