MACHINE SHOP CALCULATION - OD1640 - LESSON 1/TASK 1
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.
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
(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
(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.