 | Joseph Ray - Arithmetic - 1877 - 350 pages
...product. 2. The extremes are 2 and 50; the number of terms, 24 : find the sum of the series. 624. 3. How many strokes does the hammer of a clock strike in 12 hours? . " 78. 4. Place 100 apples in a right line, 3 yd. from each other, the first, 3 yd. from a basket... | |
 | Joseph Ray - Arithmetic - 1880 - 420 pages
...that of the extremes, and hence, as the above illustrates, the double of any such series is equal to the product of the number of terms by the sum of the extremes. FORMULA. — s =. (« + t) n. ~~2~ "Rale.— Multiply the sum of the extremes by the number... | |
 | Joseph Ray - Arithmetic - 1885 - 358 pages
...series. 2. Tho extremes are 2 and 50 ; the number of terms, 24 : find the sum of the series. Ans, 624. 3. How many strokes does the hammer of a clock strike in 12 hours? Ans. 78. 4. Find the sum of the first ton thousand numbers in the series, 1, 2, 3, 4, 5, <fec. Ans.... | |
 | Charles Austin Hobbs - Arithmetic - 1889 - 362 pages
...terms of the series 24, 22£, 21, etc. 12. Find the sum of the odd numbers from 1 to 49 inclusive. 13. How many strokes does the hammer of a clock strike in 12 hours ? 14. How far can a man walk in 10 days, going 12 miles the first day, and increasing the rate 3 miles... | |
 | George Albert Wentworth - Arithmetic - 1896 - 490 pages
...Therefore, we have the following rule for finding the sum of an arithmetical progression : Take half the product of the number of terms by the sum of the first and last terms. Find the sum of nine terms of an arithmetical progression whose first term is 3 and last term 41. EXERCISE... | |
 | George Albert Wentworth - Arithmetic - 1897 - 480 pages
...Therefore, we have the following rule for finding the sum of an arithmetical progression : Take half the product of the number of terms by the sum of the first and last terms. Find the sum of nine terms of an arithmetical progression whose first term is 3 and last term 41. EXERCISE... | |
 | George Wentworth, David Eugene Smith - Arithmetic - 1909 - 290 pages
...the sum is J of 7 x 14, or 49. Therefore, to find the sum of an arithmetical progression, take half the product of the number of terms by the sum of the first and last terms. Thus the sum of nine terms of an arithmetical progression whose fust term is 3 and last term 41, is... | |
| |
Hence, the sum of a series of numbers in progression by difference is one half of the product of the number of terms by the sum of the first and last terms. 
