Teacher2Teacher Q&A #19681

Teachers' Lounge Discussion: Fraction notation in algebra 1

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From: Loyd

To: Teacher2Teacher Public Discussion
Date: 2009081120:20:24
Subject: Using the divide or "per" line

A horizontal line is best, but it is hard to make that symbol on a computer so we use the slash which has been adopted by most (or some) calculator manufacturers to mean divide or in the case of percent, it means "per" which means divide. For example, one often hears miles "a" gallon when it should be miles "per" gallon. Saying it the latter way, helps to calculate the unit values. I agree with Gail's post. We should use a horizontal line especially when we are using a pencil and paper such as in class. I have seen problems when students keep using slashes versus horizontal lines. It distorts the position of the numerator and denominator and without grouping symbols gives incorrect answers. The first poster is right, the proper use of grouping symbols can prevent calculation errors. Look at this problem in the vertical three line form: 3 + 1 4 __ __ = __ 4+1 2+3 5 Compare this to the one line form often written as 3/4+1+1/2+3=5 ¼ If you are going to use the one line form, you must use grouping symbols. 3/(4+1) + 1/(2+3)=4/5 When I started writing computer programs lack of grouping symbols was often what caused programs to get incorrect answers.

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