Two tens and nine ones? you? 9. Take one more counter; add it to the twenty-nine. How many tens have Have you any ones besides the three tens ? Tie your three tens tightly together. Write the figures which stand for three tens and no ones. Three Tens Thirty Untie all the bundles. How many ones have you? Three tens are how many ones? Thirty ones are how many tens? 10. Read these numbers: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30.. Write them on your slate in a vertical column. To the left of each write the word which stands for the number. In which line do you find all the ones? In which line are the tens ? 29 ones are how many tens and ones? 2 tens and 6 ones are how many ones? Which is the greater, 2 tens or 2 ones? 11. The Roman letters, I, V, and X, are also used to represent numbers. I stands for one, V for five, and X for ten. Words: naught, one, two, three, four, five, six, seven, eight, nine. Twenty-two Twenty-three Twenty-four Twenty-five Twenty-six The Roman characters are not now employed in number work, but are chiefly used for numbering chapters and lessons, and occasionally for numbering some of the first pages in books, and in numbering appendixes and indexes. They are also used to indicate the different volumes of a series of books, and to mark the hours on the dials of clocks and watches. These uses give variety, and sometimes prevent confusion. Since you will meet these characters in nearly every book you take up, it is well that you should know what they mean. CHAPTER II. 1. Separate 21 cubes into three equal groups. 21 cubes are how many seven-cubes? 3 seven-cubes are how many cubes? 21 is how many 7's? 21 = 3 sevens. 21 ÷ 7 = 3 (21 contains 7 three times, or 21 contains 3 sevens). 3 sevens are how many? 3 sevens 21. = 3 times 7 are how many? 3 x 7 = 21. 7 is what part of 21? of 21 = ? 3 thirds of 21 are how many? How many 7's can you take out of 21 ? Begin with 7 and count 21 by 7's. 21-7-7-7=? 7+7+7= ? 2. Copy the following forms, and place together those which have the same meaning. 21 miles 7 miles = 3. 21 miles÷ 3 = 7 miles. 21 yards 37 yards. 21 yards÷7 yards = 3. 3) 21 miles to be divided. 7 miles) 21 miles. 7 miles. 3, number of 7-miles in 21 miles. 3. Helen has 21 nuts which she wishes to share equally with two playmates. How many nuts will each receive? Into how many equal groups must the nuts be divided? There are three children, so the nuts must be divided into three equal groups. We count off one to each child in turn, until we have used all the nuts. First child, Third child, Each child will get of 21 nuts, which is 7 nuts. Slate work: 3) 21 nuts, to be divided. 7 nuts, each one receives. Divide 21 sheets of paper equally among 3 pupils. How many sheets will each pupil receive? What part of the paper will each get? (Make picture.) Make a problem for this form of 21 = 7. 4. I have 21 cents to spend for Christmas cards; if I pay 7 cents apiece, how many can I buy? ୦୦୦୦୦୦୦ ୦୦୦୦୦୦୦ ୧୦୦୦୦୦୦ I can buy 1 card for 7 cents. I can buy as many cards for 21 cents as there are 7-cents in 21 cents. There are three 7-cents in 21 cents. 3 cards at 7 cents each. Slate work: 7 cents) 21 cents. 21 cents will buy 3 (7-cents in 21 cents). 21 cents will buy 3 cards at 7 cents each. At 7 cents each, how many cakes can George get for 21 cents? (Make a picture for this problem. Express in figures.) NOTE TO THE TEACHER. The picture language and the arithmetical form should be closely connected at this step: the one explains the other. No explanation should be learned as a formula. 5. Divide 21 cakes equally among 3 children. How many will each receive? (Picture figures.} At $7 each, how many lamps can be bought for $21? I have $21 to spend for 3 birthday presents. If I divide the money equally, what must I pay for each? One of the three equal parts of 21 cents is how many cents? 21 cents contains 7 cents how many times? |