Working with Fractions (Math for the Trades)

Working with Fractions (Math for the Trades)

by Mary Lett

​Objective

​Students will be able to identify parts of a fraction, convert between improper fractions and proper fractions, write fractions in lowest terms, calculate pitch of a roof, and compare fractions.

​Parts of a Fraction

• ​Numerator: the upper number; counts the number of parts we have

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• ​Denominator: the lower number; names the total parts in whole

Multiple Choice

The BOTTOM part of the fraction is known as

• whole number

• numerator

• denominator

Multiple Choice

The TOP part of the fraction is known as

• numerator

• denominator

• whole number

​Proper and Improper Fractions

​Mixed Numbers

• ​Mixed Number: an improper fraction written as the sum of a whole number and a proper fraction.

Multiple Choice

Write 15/4 as a mixed number.

• 3 3/4

• 3 1/4

• 4 1/4

• 4 1/5

Multiple Choice

Write 23/7 as a mixed number.

• 2 3/7

• 3 1/7

• 3 2/7

• 4 2/7

Multiple Choice

The simplified improper fraction of this mixed fraction is ...

• 19/9

• 13/9

• 93/9

• 31/3

Multiple Choice

The improper fraction of this mixed fraction is ...

• 6/5

• 11/5

• 26/5

• 5/5

​Equivalent Fractions

• ​Equivalent Fractions: when two fractions represent the same number.

Multiple Choice

Which fraction is equivalent to 1?

• 1/2

• 1/10

• 5/5

• 5/1

Multiple Choice

Complete the equivalent fraction.

• 6

• 9

• 15

• 23

​Lowest Terms

• ​Lowest terms: the simplest equivalent fraction

Fill in the Blank

Write ⁷⁷/₁₃₂ in lowest terms

Fill in the Blank

Write ⁴/₁₈ in lowest terms

​Pitch of a Roof

• ​Pitch: steepness of a roof

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• ​rise: the increase in height

• run: the corresponding horizontal distance

​Comparing Fractions

• ​To compare fractions you must rewrite them with a common denominator.

Multiple Choice

Which is thicker, a 3/16 in sheet of metal or a 13/64 in fastener?

• 3/16 in sheet of metal

• 13/64 in fastener

Fill in the Blank

A ridge beam rises 18 in. over a horizontal run of 72 in. Calculate the pitch of the roof and express it as a fraction with a denominator of 12.

Fill in the Blank

A 3/4 in. drill bit is too large for a job, and an 11/16 in. bit is too small. What size should be tried next?