3. Walter weighs 961 lb. and Henry weighs 897 lb. How much more does Walter weigh? 961/4 89% 63% Think, “7 and make 1." Add 1 and 1, making 3. Write, carry 1. When the fraction above is smaller than the one below it, the steps are: (1) find how much more with the lower fraction makes 1; (2) then add the result to the upper fraction; (3) and write the result and carry 1. PRACTICE IN SUBTRACTION You have found three kinds of problems in subtraction. They are like the three following groups. Practice until you can do each quickly. Always check your work. A RACE IN SUBTRACTION All begin at a signal from the teacher. All stop when one has finished all. Correct your work and see who won. 25. 1 -1 1. 吾 - 素 = = 26. 1 27. 1 3. 4. 공 5. = 50. 11/ = 51. 1 = 52. 11 = 53. 11 54. 1층 1 = = = 1 = 1. Into how many equal parts is rectangle A divided? What is each part called? How many parts are shaded? Express the shaded portion as a fraction. 2. What fractional part of rectangle B is shaded? 3. What fractional part of rectangle C is shaded? 4. How many numbers are needed to express a fraction? 5. What does the number above the line show? 6. What does the number below the line show? The two numbers used to express a fractional part of a whole are called its terms. The term below the line names the fraction by showing the number of parts into which the whole was divided and is called the denominator (namer). The term above the line shows how many parts are taken to make up the fraction and is called the numerator (numberer). 7. Write a fraction whose numerator is 3 and whose denominator is 8. Read the following fractions and give the name of each term: 8. 1, §, 7, 10 10. Which is more, 2 5 7 9. 3, 3, 4, 8, 12 of anything or of it? Tell why. 11. If you double the numerator of a fraction, what effect does it have on the size of the fraction? CHANGING FRACTIONS TO LARGER OR SMALLER TERMS 1. When one half of a rectangle was divided into two equal parts, it gave a new fraction each of whose terms was how many times the corresponding terms of ? 2. The terms of are each how many times the corresponding terms of ? Of 2? 3. Draw a rectangle and divide it into thirds. Now divide each third into two equal parts. What are the new parts called? From the rectangles given here and from those which you made, it is seen that The form of a fraction may be changed by multiplying both terms by the same number without changing the part of the whole which the fraction represents. Both terms of a fraction may be divided by the same number without changing the size of the part which the fraction represents. The process of changing the form of a fraction without changing its value is called reduction. Fractions are reduced to smaller terms or to larger terms, when such a change is necessary. |