**MACHINE SHOP CALCULATION - OD1640 - LESSON 1/TASK 1**

FIGURE 2.

FRACTIONAL PARTS OF A UNIT.

(2) *Terms of a Fraction*. The numerator and the denominator are called the

terms of the fraction. The terms are indicated by a diagonal line (/).

(a) *Numerator*. The number above the diagonal line is the numerator.

It

indicates the quantity of equal parts to be considered.

(b) *Denominator*. The number below the diagonal line is the denominator.

It indicates the quantity of equal parts into which the whole unit has been

divided.

(3) *Common Denominator*.

When two or more fractions have the same

denominator, such as 2/5 and 4/5, the 5 is known as the common denominator.

(4) *Least Common Denominator (LCD)*. The LCD of two or more fractions is

the least common multiple of the denominators of all the fractions under

consideration. For example in 5/7, 1/7, 3/7, the 7 is the LCD. When the

denominators are not the same, as in 3/4, 2/5, and 7/10, the LCD is 20,

because 20 is the smallest number containing 4, 5, and 10 a whole number of

times.

(5) *Proper Fraction*. This is a fraction having a numerator less than the

denominator. In other words it is a true fraction of a single whole, such

as 9/10 or 7/8 or 21/23.

**6**