572. Oral Exercises.

How many square feet in a rectangle 2 feet long, 1 foot wide? 6 feet long by 5 feet wide? 9 feet long by 7 feet wide?

574. NOTE. Change the inches to fractions of a foot.

Measure the top of the desk, and calculate the surface in square inches. (Do not include fractions of an inch.)

Measure the blackboard, and find how many square feet in its surface. (Do not include fractions of a foot.)

Calculate the number of square inches in a pane of glass in the school-room window.

Find the number of square feet in the floor of the class-room. Find the number of square feet in the class-room ceiling. Estimate the height of the class-room, and calculate the number of square feet in the front wall. In the rear wall. In the right-hand wall. In the left-hand wall.

576. Slate Problems.

SUGGESTION. When the surface is required in square inches, change each dimension to inches; when required in square feet, express each dimension in feet, or in feet and the fraction of a foot; when required in square yards, etc., express each dimension in yards, etc.

1. How many square feet are there in the surface of a field 125 feet long, 87.5 feet wide?

2. A rug is 2 yards long, 13 yards wide. How many square yards does it contain?

3. How many square yards are there in a strip of carpet 6 yards long, 27 inches ( yd.) wide?

4. Find the number of square meters in a room 12 meters long, 9.75 meters wide.

5. At 50 cents per square yard, what will be the cost of the oil-cloth needed to cover a floor 18 feet (6 yd.) long, 15 feet (5 yd.) wide?

6. What will be the cost, at $1.50 per square yard, of carpeting a room 61 yards long, 15 feet wide?

7. At 3 cents a square foot, how much must be paid for 10 boards, each 16 feet long, foot wide?

8. A field is 30 rods long and 24 rods wide. How many square rods will it contain after a strip 24 rods long and 2 rods wide is taken from it for a road?

9. How many square yards of plastering will be required for a ceiling 18 feet long, 15 feet wide?

10. If a roll of wall paper is 24 feet long and 18 inches wide, how many square yards does it contain?

Since 9 is a multiple of 3, any multiple of 9 will be a multiple of 3. Omitting the latter number, we find the least common multiple of 8 and 9, 72, which is the least common denominator of the fractions.

2. Add 21, 4, 54, 43

Omitting 4, which is a factor of 8, we find the least common multiple of 3, 7, 8.

6. 29+45 +16

7. } + { + # +8

10.

882-1887

L. C. M. of 15 and 6 = ?

8. 11+53 +135+83+ 195 9. 8+373 +28+ 92% +19 +28+81%+15%

582. A number that has no factors is a prime number. 1, 2, 3, 5, 7, etc., are prime numbers.

583. 1. Name the prime numbers between 10 and 20.

2. Between 20 and 30.

3. Between 30 and 50.

584. Sight Exercises.

4. Between 50 and 70.

5. Between 70 and 100.

Give the prime factors, commencing with the smallest.