THE NEW STUDENT'S REFERENCE WORK 2177
SUBTRACTION OF FRACTIONS.
Eule for subtraction of fractions. Change both fractions to similar fractions and find the difference of the numerators. Write the result over the common denominator and reduce to simplest form.
From f take |
- = *
i = t
§—i=f—i=i
Prom 25£ take 9|
25*4
9||
16 I
From 255 take 9J 25ff
MA 154
Subtraction examples:
•i-I
i -1 ii — H
To subtract one mixed number from another, change the fractions to similar fractions and subtract.
As we cannot take |- from f, we change 1 unit of the 25 to 8ths, which with | = V" — 4 = * 24 — 9 = 15.
A- f
I - t i - i
- - I 56T\ - 32J
15i — 12i
15| — 7| 29i — 25| 54| -22| 72 -48&
MULTIPLICATION OF FRACTIONS.
Review. The numerator of a fraction shows the number of parts. The denominator shows the size of each part.
To multiply % by 2 we may multiply the number of parts 2 X I = f =f, or make each part twice as large by dividing the denominator.
A 'fraction is multiplied by multiplying the numerator, or by dividing the denominator.
Multiply 78 by 4.
Every whole number, or integer, may be considered the numerator of a fraction whose denominator is 1. Therefore 4 may be written f.
g X 4 = ^ == \ — 3J. Cancel when possible.
3
Multiply, cancelling when possible:
f X 4 f X 2 T\X5 AX 4 AX6 *X7
27 X |
36 X H 124 X I 54 X if 45 X TV 16 X I
A X 5 S X 6 H X10
II X21 f| X 22 i%X12
11 X T!T 8X A
12 X H 36 X if 16 X H
120 x H
