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

f.

*Finding the Least Common Denominator of a Group of Fractions Having*

*Different Denominators*.

*Rule 1*. To find the least common denominator of a group of fractions having

different denominators, divide the given denominators by a prime number (a

number divisible only by itself and 1) which will divide two or more of

them.

Similarly, divide the remaining numbers and their quotients.

Continue this as long as possible. The LCD (least common denominator) will

be the product of the divisors and the quotients of numbers left.

EXAMPLE

Find the LCD of 4/5, 5/6, 7/9, and 9/10.

Step 1.

Divide the denominators 5 and 10 by the prime number 5.

Write 1

under the 5 and 2 under the 10.

Step 2.

Bring down the denominators 6 and 9 as shown.

Step 3.

Divide the denominators 6 and 9 by the prime number 3.

Bring

down the other digits (remaining numbers), 1 and 2.

Step 4.

Divide the digits (remaining numbers, 2 and 2, by the prime

number 2.

Bring down the digits (remaining numbers), 1 and 3.

The remaining numbers 1 will not reduce any further as a whole

number, and 3 is divisible by 3, but there is no second

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