if you do 10 20 30 40 50 60 70.... you will see what times what gives you 60 which in this case it is what times 6 gives you 60 so if you list your 6s you will will go until you get to 6*10 which is 60 but you can do a list of your 10s it is easier that away to be honest. I hope this answer helps you:)
