Sam has cards that are numbered one to eight. Sam turns over two of the cards: eight, one, five, what, what, two, four, seven. Which two cards has Sam turned over? Write the numbers on the cards below.
We know that Sam has cards that are numbered one to eight. So these are the cards which Sam should have: one, two, three, four, five, six, seven, and eight. We also know that Sam turns over two of the cards. So we need to work out which two cards Sam turned over and write them in the blank cards below.
Let’s start at number one and check each digit in turn. So the cards we can see are number one, number two. We can’t see a card with a number three. Now we know one of the missing cards, or one of the cards that Sam turned over, is a number three. We can see a number four and a number five. But there’s no number six. So we can see that number six must be the second card that Sam turned over.
We can quickly check to see if number seven and number eight are turned over. We can see them. So we can take them off our list. So the two cards that Sam has turned over are numbers three and six.