How to Correctly Work Through a Math Problem
To evaluate (or solve) a math expression, you need to perform the steps in the correct order. Students in elementary and middle school math classes study the so-called order-of-operations rules so they'll have a solid foundation to move on to more complex expressions and equations. Keep in mind the acronym PEMDAS (parentheses, exponents, multiplication/division, addition/subtraction) to commit the order of operations to memory.
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Instructions
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Calculate operations inside parentheses. If there are a lot of parentheses in a row, start with the one on the left and work your way to the right. If the parentheses are nested inside each other, start with the most nested set of parentheses and work your way out. Note that working with parentheses may involve either solving the expression inside the parentheses or distributing across the terms inside the parentheses.
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Look for exponents. Exponents are those numbers in superscript above and to the right of a base. To get rid of exponents, you will either solve the term or distribute the exponent across a group of terms set off by parentheses. For example, 5^2 equals 25.
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Seek out opportunities to multiply or divide next. Start at the beginning of the expression and deal with the first multiplication or division sign you see by solving that bit of the expression. It doesn't matter which you run into first, but it is important that you solve all multiplication and division in order from left to right prior to moving on to addition and subtraction. For example, in the expression 25 / 5 x 4 / 2, begin with 25/5 = 5. Then calculate 5 x 4 = 20 and finally 20 / 2 = 10.
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Deal with the last operations, addition and subtraction, the same way. Start at the beginning of the expression and solve the first addition or subtraction sign you see. Continue this way until you have nothing left to solve. For example, in 18 + 3 - 5 - 12, calculate 18 + 3 = 21; 21 - 5 = 16. Find the answer by subtracting 12 from 16 to get 4.
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Tips & Warnings
To remember the order of operations, remember the acronym PEMDAS (parentheses, exponents, multiplication/division, addition/subtraction).
Calculate multiplication and division together from left to right; follow the same procedure with addition and subtraction.
References
- Photo Credit Digital Vision./Digital Vision/Getty Images
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Comments
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kirylin
Oct 03, 2008
Yes, it should. This is what I get for video editing while sick! ;) Thanks for letting me know. -
icanu2
Oct 03, 2008
In the last problem in the video the slide shows 6/3 = 3 ! Must be a typo because 6/3 = 2. Other than that part I found your how to very helpful. Now if I can get my kids to use your tips.
