17. James had 96 marbles; he gave away 24, and lost 36. How many had he left? 18. A certain boat has a crew of 18 persons, and 73 passengers on board. If 53 persons get off, how many are left aboard? 19. P had $20, and earned $13 more. Q had $46, and spent $19. Which then had the most, and how much? 20. An orchard of apple, pear, and cherry trees, contains 200 trees in all. If there are 125 apple trees, and 46 pear trees, how many cherry trees are there? 21. A farmer, who had made 336 pounds of butter, sold 110 pounds to one customer, and 127 to another; how many pounds were left? 22. If a person gets 14 quarts of strawberries from one bed, 19 from another, and 23 from a third, how many quarts will he have left after selling 37 quarts? 23. If a person gets 29 quarts of strawberries from one bed and 38 from another, how many quarts will he have left after selling 17 quarts and giving 25 away? 24. A and B start from two places 96 miles apart, and travel toward each other. The first day, A goes 48 miles, and B 27; how many miles are they then apart? How far is A from B's starting-place? How far is B from A's starting-place? 25. What number must you add to the sum of nine, thirteen, and forty-eight, to produce 99? 26. There are sixty-six rows of corn to hoe in one field, and forty-three in another. When Robert has hoed 19 rows, Richard 23, and Reuben 27, how many rows still remain to be hoed? CHAPTER THIRD. MULTIPLICATION. SECTION 7-Multiplication is the process of taking a number a certain number of times. Makiplication is denoted by a slanting cross X, placed between the numbers to be multiplied together. 2 × 3 is read two multiplied by three, and means two taken 3 times. 2x3=6. We have multiplied 2 by 3; the result, 6, is called their Product. 1. How much is 3 times 4? 4 times 9? Twice 12? 4 times 6? 9 times 2? 8 times 4? 2. What is the product of 4 and 2? 9 and 6? 6 and 7? 11 and 3? 11 and 4? 12 and 6? 8 and 3? 3. How much is 12 × 5? 6x8? 3×9? 8x7? 10x6? 5x11? 12 x3? 4 x 10? 4. Multiply 8 5 by 5. 3 by 3. by 8. 7x7? 4 by 4. 6 by 6. 11 by 11. 5. How much is 12 times 7? 7 times 12? 6 times 11? 11 times 6? 3x4x2? 2×4×3? 6. When numbers are to be multiplied together, does the order in which they are taken affect the product? 7. How much is 7 times 9? 9 times 7? Twice 9. When 10 is a factor, with what figure does the product always end? 10. How much is 5x1? 5x9? 5x3? 5×7? 5×2? 5x6? 5×8? 6x5? 9x5? 11. When 5 is a factor, with one of what two figures does the product end? 12. What will 9 tops cost, at 5 cents apiece? MODEL. Nine tops will cost 9 times as much as 1 top. If 1 top costs 5 cents, 9 tops will cost 9 times 5, or 45, cents. Ans. 45 cents. 13. What will 8 knives cost, at 6 dimes each? 14. At 12 cents each, what will 9 primers cost? 19. If a boat moves at the rate of 11 miles an hour, how far will it go in 11 hours? MODEL. In eleven hours it will go 11 times as many miles as in 1 hour. If in 1 hour it goes 11 miles, in 11 hours it will go 11 times 11, or 121, miles. Ans. 121 miles. 20. How far will a stage, moving at the rate of 7 miles an hour, go in 6 hours? In 10 hours? 21. How many apples in 5 baskets, each containing 12 apples? 22. How many fingers have 11 persons? 23. How many thumbs have 8 persons? 24. If a boy earns $10 a week, how many dollars will he earn in 4 weeks? In 6 weeks? In 9 weeks? 25. How many chickens in eleven broods, containing nine chickens each? 26. Paid $5 for a lamp, and $1 for a shade. How much will four such lamps and shades cost? 27. At the rate of 7 dimes for a knife, and 2 dimes for a fork, what will 12 knives and forks cost? 28. Four pens, each containing 5 pigs, hold how many pigs in all ? 29. 5×4 how many? 30. 5+5+5+5=how many? 31. Multiplication is a short way of performing what other process? Prove this in the case of six times three. SECTION 8.-1. How much is twice 34 ? MODEL. Twice 4 units is 8 units; twice 3 tens is 6 tens. 6 tens and 8 units are 68. Ans. 68. 4 times 120? 311 × 3? 101 x 4 ? 102 × 3 ? 9 times 100 ? 22 × 4? 2. How much is 3 times 23 ? 3. How much is twice 21? 4. How much is twice 44 ? 5. How much is 4 times 1000? 6. How much is 3 times 2000? 7. How much is 10 times 7? times 10? 10 times 100? 10 times 17? 7 times 101 ? 10 times 9? 10 8. How do we multiply a number by 10? 9. How much is 100 times 2? 100 times 9? 100 times 20? 100 times 35? 100 times 68? 10. What easy way is there of multiplying by 100? 13. How much is 2000 times 7? 9 × 20? 14 x 20? 200 times 9? 2000 times 9? MODEL. 4 times 1 unit is 4 units; 4 times 9 tens is 36 tens, or 3 hundreds and 6 tens. 3 hundreds 6 tens and 4 units are 364. 364. Ans. 15. How much is 5 times 61? 4 times 72 ? 16. How much is twice 640 ? 8 times 61? 17. If there are 144 steel pens in one box, how many are there in two boxes? 18. How many pages are there in 10 volumes, containing 288 pages each? 19. How many trees has a nurseryman, if he has 100 rows of 17 each? 20. How many pills are there in 200 boxes, each containing 24 pills? |