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Question on fixing extra string error

Hi, I’m currently going over how to use Sprintf in golang and I came across an extra error. The code is:
package main
import “fmt”

func main() {
	name := "Caprica-Six"
	six := "6"
	aka := fmt.Sprintf("Number ",six)
	fmt.Printf("%s is also known as %v",
		name, aka) //printing variables within the string
}

and the result is: Caprica-Six is also known as Number %!(EXTRA string=6). Why is that extra string bit popping up?