Denominate Numbers — Weight, 350. Troy weight is used in weighing gold, silver, and jewels. TROY WEIGHT. = 1 pound (lb.). 351. Apothecaries' weight is used in mixing medicines and in selling them at retail. APOTHECARIES' WEIGHT. 20 grains (gr.)= 1 scruple (O). NOTE 1. - The pound Troy and the pound Apothecary are equal, each weighing 5760 grains. The pound Avoirdupois weighs 7000 Troy or Apothecary grains. NOTE 2. — The ounce Troy and the ounce Apothecary are each 486 grains; the ounce Avoirdupois is 4371 grains. QUERY. — Which is heavier, a pound of feathers or a pound of gold? An ounce of feathers or an ounce of gold ? PROBLEMS. 1. Change 5 lb. Avoirdupois weight to pounds, ounces, etc., Apothecaries' weight. 2. How many 5 gr. powders can be made from one Avoirdupois ounce of quinine? 3. One Avoirdupois ton of gold is how many Troy pounds? 4. Twenty-four Troy pounds equal how many Avoirdupois pounds ? (P. 379.) 352. MISCELLANEOUS TABLES. 12 units 1 dozen. 20 units = 1 score. 24 sheets (paper)= 1 quire. 1 great gross. 20 quires = l ream. 1 gross. 12 gross 353. APOTHECARIES' FLUID MEASURE. 60 minims (m) = 1 fuid dram (f 3). 8 fluid drams = 1 fluid ounce (f 3). 1 gallon (Cong.). = 354. ANGULAR MEASURE. 355. MEASURE OF TIME. 60 seconds (sec.)= 1 minute (min.). = 1 day (da.). 1 week (wk.). 365 days =1 common year. 52 wk. 1 da. = 1 common year. 366 days = 1 leap year. 52 wk. 2 da. : 1 leap year. = (P. 379.) “So tcach us to number our days that we may apply our hearts unto wisdom." וי SHORT METHODS IN MULTIPLICATION AND DIVISION. Art. 1. To multiply a number by 50: Multiply 1 of the number by 100. Why? 46 x 50 1 of 46 x 100 = 2300 Multiply: 82 by 50 76 by 50 43 by 50 Art. 2. To multiply a number by 51: Take 50 times the number, to which add the number itself. Why? 48 x 51 50 times 48 = 2400 2400 + 48 = 2418 Multiply: 66 by 51 84 by 51 33 by 51 = 2250 Art. 3. To multiply a number by 52: Take 50 times th. number, to which add twice the number. Why? 34 x 52 50 times 34 = 1700 1700 + 68=1768 2250 + 90 = 2340 36 by 52 44 by 52 23 by 52 (c) Find the sum of the twelve products. Art. 4. To multiply a number by 49: Take 50 times the number, from which subtract the number itself. Why? 24 x 49 50 times 24=1200 1200 - 24 = 1176 Multiply: 26 by 49 38 by 49 31 by 49 (d) Find the sum of the twelve products. Art. 5. To multiply a number by 331: Multiply of the number by 100. Why? 36 x 33} of 36 x 100 = 1200 37 x 331 Žof 37 x 100 = 1233} Multiply: 28 by 333 41 by 333 Art. 6. To multiply a number by 343: Take 333 times the number, to which add the number itself. Why? 24 x 343 33] times 24 = 800 800 + 24 = 824 25 x 343 333 times 25 = 833} 833} + 25 = 8583 Multiply: 18 by 343 27 by 343 24 by 343 33 by 313 39 by 34} 15 by 343 'f) Find the sum of the twelve products. Art. 7. To multiply a number by 353: Take 33} times the number, to which add twice the number. Why? 24 x 35} 33} times 24 = 800 800 +48= 848 25 x 353 33] times 25 = 833} 833} + 50 = 8831 Multiply: 66 by 35} 36 by 35} 42 by 35} (g) Find the sum of the twelve products. Art. 8. To multiply a number by 321: Take 333 times the number, from which subtract the number itself. Why? 21 x 321 331 times 21 = 700 700 21= 679 22 x 32} 33} times 22= 733} 733– 22 = 7111 Multiply : 18 by 321 27 by 32} 36 by 321 19 by 32 20 by 321 |