Εικόνες σελίδας
PDF
Ηλεκτρ. έκδοση

ORAL DRILL

In each of the following examples, find the sum of the

[merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
[ocr errors]

Fractions Whose Numerators Are 1.- When two fractions are to be added where both numerators are 1, and the denominators are prime to each other, observe the following rule.

Rule. (1) Add the denominators together for the numerator of the answer; (2) multiply the denominators together for the denominator of the answer.

EXAMPLE. Add and .

4+5=9, the numerator of the answer;

4 x 5 =

20, the denominator of the answer.

Then += 2%, the sum.

20

ORAL DRILL

In each of the following examples find the sum of the numbers given.

[ocr errors][merged small][merged small][merged small][merged small][merged small]
[merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

In the subtraction of fractions, as in their addition, the denominators must be made equal.

Rule. To subtract one fraction from another, (1) reduce them to similar fractions having the least common denominator, (2) write the difference of the numerators over the least common denominator, and (3) reduce the result to lowest terms.

[blocks in formation]

In each of the following examples, find the difference between the numbers given:

[blocks in formation]
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small]

Prime Denominators.

When the numerator of each

fraction is 1, and the denominators are prime to each other, observe the following rule.

Rule. (1) Find the difference of the denominators for the numerator of the answer; (2) multiply the denominators together for the denominator of the answer.

EXAMPLE.

From

5 4:

4 x 5

=

=

subtract .

1, the numerator of the answer;

20, the denominator of the answer.

Then, the difference.

[ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

ORAL DRILL

In each of the following examples find the difference between the numbers given.

2.

1

29

[ocr errors]
[blocks in formation]
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small]
[ocr errors]

Mixed Numbers. When the numbers are mixed numbers and the fractional part of the subtrahend is greater than the fractional part of the minuend, observe the following rule.

Rule. (1) Increase the fraction in the minuend by 1,

(2) decrease the whole number by the same amount, and (3) proceed as before.

EXAMPLE. From 7 take 43.

73=728% = 628

43 = 415 = 415

218, the difference.

It will be observed in the fraction

nominator are added, the sum is the numerator of the fraction at the

that if the numerator and de

right.

Exercise

In each of the following examples, find the difference between the numbers given:

[blocks in formation]

Using the best method in each case, find in the first fifteen of the following examples the difference between the numbers given, and in the last seventeen, the sum:

[blocks in formation]
[blocks in formation]

Multiplication and Division of Fractions

In the multiplication and division of fractions it is well to keep in mind the following Principles:

1. Multiplying the numerator multiplies the fraction. 2. Multiplying the denominator divides the fraction. 3. Dividing the numerator divides the fraction.

4. Dividing the denominator multiplies the fraction.

5. Multiplying both numerator and denominator by the same number does not change the value of the fraction.

6. Dividing both numerator and denominator by the same number does not change the value of the fraction.

[ocr errors]

Multiplication of Fractions

Rule. To multiply one fraction by another: (1) multiply the numerators together for the numerator of the answer; (2) multiply the denominators together for the denominator of the answer.

EXAMPLE 1. Multiply by .

Then

2 x 48, the numerator of the answer;

3 x 5 = 15, the denominator of the answer.

=

8

When a fraction is to be multiplied by a whole number the whole number can be considered as a fraction whose denominator is 1.

[merged small][ocr errors]
« ΠροηγούμενηΣυνέχεια »