In the same manner in which you made the cards for the Letter Game
prepare a set on which are numbers instead of letters. Follow the same
rules for the Number Game, using rows of numbers instead of letters.
First use a row of single digits, increasing it until you have used
nine or ten. Then change and arrange a column of two digits, as
illustrated below.
Later for variety you can combine letters and numbers. In some
arrangements leave blank spaces requiring the child to leave the blank
in its proper location when reproducing his mental picture.