Example 2: Multiply 31.56 by 5.49.
| 31.56 | ||
| 5 | .49 | |
| 157.80 | ||
| 12.62 | 4 | |
| 2.84 | 04 | |
| 173.26 | 44 | Ans. |
As before, place the unit’s figure of the multiplier—that is, the 5—under the right-hand digit of 31.56, and proceed as above.
Note.—The number of decimal places in the product will always be equal to the sum of the number of decimal places in the multiplier and the multiplicand. Thus, in Example 2, there are two places of decimals (i.e. two figures to the right of the point) in 31.56, and two places of decimals in 5.49; and we found 2 + 2 = 4 places in the product 173.2644.
To multiply a decimal by 10, 100, etc.
Rule.—Remove the (.) as many places to the right as there are ciphers in the multiplier.
| Work: | 8.75 | × | 10 | = | 87. | 5 |
| 8.75 | × | 100 | = | 875. | ||
| 8.75 | × | 1000 | = | 8750. |
Division of Decimals
Rule.—Divide as in whole numbers, annexing ciphers to the dividend, if necessary; then point off from the right of the quotient as many places as the decimal places in the dividend exceed those in the divisor—prefixing ciphers if necessary.
(a) Division of a decimal by a whole number.