A mixed number is made up of a whole number with some decimal fraction, the one being separated from the other by a point, thus 3·25 is the same as 3 25 100 or 325 100 .
Ciphers on the right hand of decimals make no alteration in their value; for ·5, ·50, ·500 are decimals having all the same value, each being = 5 10 . But when they are placed on the left hand, they decrease the value in a tenfold proportion; thus, ·5 is 5 10 ; but ·05 is 5 100 .
ADDITION OF DECIMALS.
Rule.—Set the numbers under each other, according to the value of their places, in which state the decimal separating points will all stand exactly under each other. Then beginning at the right hand, add up all the columns of numbers as in integers, and point off as many places for decimals as are in the greatest number of decimal places in any of the lines that are added; or place the point directly below all the other points.
Example.—Required the sum of 29·0146, 3146·5, 14·16, and 165.
| 29·0146 | |
| 3146·5 | |
| 14·16 | |
| 165· | |
| Answer | 3354·6746 |
SUBTRACTION OF DECIMALS.
Rule.—Place the numbers under each other according to the value of their places. Then, beginning at the right hand, subtract as in whole numbers, and point off the decimals, as in addition.
Example.—Subtract 4·90142 from 214·81.