GED Math : Order of Operations

Study concepts, example questions & explanations for GED Math

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Example Questions

Example Question #1 : Order Of Operations

Evaluate:

\(\displaystyle 6 \times 3 + 4 ^{2}\)

Possible Answers:

\(\displaystyle 26\)

\(\displaystyle 34\)

\(\displaystyle 484\)

\(\displaystyle 294\)

\(\displaystyle 1,764\)

Correct answer:

\(\displaystyle 34\)

Explanation:

Work the operations in this order: Square first, multiply second, add third.

\(\displaystyle 6 \times 3 + 4 ^{2} = 6 \times 3 +\left ( 4 \times 4 \right ) = 6 \times 3 + 16 = 18 + 16 = 34\)

Example Question #1 : Order Of Operations

Solve:

\(\displaystyle 3-4+2^{3}*3\)

Possible Answers:

\(\displaystyle 23\)

\(\displaystyle 25\)

\(\displaystyle 31\)

\(\displaystyle 15\)

\(\displaystyle 21\)

Correct answer:

\(\displaystyle 23\)

Explanation:

When solving this problem, you need to remember order of operations, which tells us which operation has to be done first.

When following order of operations, you complete operations in the following order:

1. Parenthesis - Complete any operation in parenthesis first

2. Exponents - Solve exponents second

3. Multiplication and Division - Multiply or Divide (whichever one comes first from left to right)

4. Addition and Subtraction - Add or Subtract (whichever one comes first from left to right)

Keeping order of operations in mind, the steps to solve \(\displaystyle 3-4+2^{3}*3\) are below

\(\displaystyle 3-4+2^{3}*3 \textup{ } (\textup{Solve for the exponent})\)

\(\displaystyle 3-4+8*3 \textup{ } (\textup{Multiply } 8 \textup{ and }3)\)

\(\displaystyle 3-4+24 \textup{ } (\textup{Subtract } 3 \textup{ and }4)\) 

\(\displaystyle -1+24 \textup{ } (\textup{Add } -1 \textup{ and }24)\)

\(\displaystyle 23\)

Example Question #1 : Order Of Operations

Define an operation \(\displaystyle \bigstar\) on the real numbers as follows:

\(\displaystyle a \bigstar b = \frac{a + 5}{a + b + 5}\)

Evaluate \(\displaystyle 6 \bigstar (- 6)\)

Possible Answers:

\(\displaystyle 2\frac{1}{5}\)

\(\displaystyle -\frac{1}{5}\)

Undefined

\(\displaystyle -\frac{1}{6}\)

Correct answer:

\(\displaystyle 2\frac{1}{5}\)

Explanation:

Substitute 6 for \(\displaystyle a\) and \(\displaystyle -6\) for \(\displaystyle b\):

\(\displaystyle a \bigstar b = \frac{6 + 5}{6 + (-6) + 5}= \frac{11}{0 + 5} = \frac{11}{5} = 2\frac{1}{5}\)

Example Question #2 : Order Of Operations

Define an operation \(\displaystyle \bigstar\) on the real numbers as follows:

\(\displaystyle a \bigstar b = \frac{a + 5}{a + b + 5}\)

Evaluate \(\displaystyle 7 \bigstar \left (- 12 \right )\)

Possible Answers:

\(\displaystyle -\frac{1}{2}\)

\(\displaystyle -\frac{7}{24}\)

Undefined

\(\displaystyle \frac{1}{2}\)

Correct answer:

Undefined

Explanation:

Substitute 7 for \(\displaystyle a\) and -\(\displaystyle 12\) for \(\displaystyle b\):

\(\displaystyle a \bigstar b = \frac{a + 5}{a + b + 5}\)

\(\displaystyle 7 \bigstar -12 = \frac{7 + 5}{7 + (-12)+ 5} = \frac{12}{-5+ 5} = \frac{12}{0}\)

Any fraction with a zero denominator - such as this one - is an undefined quantity.

Example Question #4 : Complex Operations

Solve:  \(\displaystyle -2 + 3\times6-12\div3+2\)

Possible Answers:

\(\displaystyle 16\)

\(\displaystyle 14\)

\(\displaystyle -4\)

\(\displaystyle \frac{10}{3}\)

\(\displaystyle -\frac{6}{5}\)

Correct answer:

\(\displaystyle 14\)

Explanation:

This problem involves order of operations.

Use the acronym for the correct order:

PEMDAS-Parenthesis, Exponents, Multiply, Divide, Add, Subtract

(Please Excuse My Dear Aunt Sally)

 

Start by grouping what needs to be solved first.

\(\displaystyle -2 + 3\times6-12\div3+2\)

\(\displaystyle -2 +\left ( 3\times6 \right )-\left (12\div3 \right )+2\)

\(\displaystyle -2+18-4+2\)

 

The answer is 14.

Example Question #1 : Order Of Operations

In order to calculate 

\(\displaystyle 50 - 20 \div 5 + 8^{2}\)

what step must you take first?

Possible Answers:

Adding five and eight

Dividing twenty by five

Calculating the square of eight

Subtracting twenty from fifty

Correct answer:

Calculating the square of eight

Explanation:

By the order of operations, in the absence of grouping symbols, exponents must be carried out before any other operations. The correct choice is that eight must be squared.

Example Question #1 : Order Of Operations

Evaluate \(\displaystyle y ^{2} - 6y + 7\) for \(\displaystyle y = 0.5\).

Do not use a calculator.

Possible Answers:

\(\displaystyle 4.25\)

\(\displaystyle 6.5\)

\(\displaystyle -7.5\)

\(\displaystyle -9.75\)

Correct answer:

\(\displaystyle 4.25\)

Explanation:

Substitute 0.5 for \(\displaystyle y\) and follow the order of operations:

\(\displaystyle y ^{2} - 6y + 7\)

\(\displaystyle =0.5 ^{2} - 6(0.5) + 7\)

\(\displaystyle =0.25- 6(0.5) + 7\)

\(\displaystyle =0.25 - 3 + 7\)

\(\displaystyle = -2.75 + 7\)

\(\displaystyle = 4.25\)

Example Question #3 : Order Of Operations

Evaluate \(\displaystyle -7x + 13\) for \(\displaystyle x = -6\). Do NOT use a calculator.

Possible Answers:

\(\displaystyle 133\)

\(\displaystyle 55\)

\(\displaystyle -49\)

\(\displaystyle -29\)

Correct answer:

\(\displaystyle 55\)

Explanation:

Substitute \(\displaystyle - 6\) for \(\displaystyle x\) in the expression and folllow the order of operations:

\(\displaystyle -7x + 13\)

\(\displaystyle = -7 (-6) + 13\)

\(\displaystyle = +(7 \cdot 6)+ 13\)

\(\displaystyle = 42 + 13\)

\(\displaystyle = 55\)

Example Question #5 : Complex Operations

Evaluate \(\displaystyle -7 + x^{2}\)  for \(\displaystyle x = 7\)

Do not use a calculator.

Possible Answers:

\(\displaystyle -56\)

\(\displaystyle -196\)

\(\displaystyle 42\)

\(\displaystyle 0\)

Correct answer:

\(\displaystyle 42\)

Explanation:

Substitute 7 for \(\displaystyle x\) in the expression and evaluate, paying attention to the order of operations:

\(\displaystyle -7 + x^{2}\)

\(\displaystyle = -7 + 7^{2}\)

\(\displaystyle = -7 + 49\)

\(\displaystyle = +\left ( 49 - 7 \right )\)

\(\displaystyle =42\)

Example Question #6 : Complex Operations

Evaluate:

\(\displaystyle 800 - 281 + 154 - 165 + 342\)

Do not use a calculator.

Possible Answers:

\(\displaystyle -142\)

\(\displaystyle 166\)

\(\displaystyle 542\)

\(\displaystyle 850\)

Correct answer:

\(\displaystyle 850\)

Explanation:

In the order of operations, additions and subtractions are carried out from left to right:

\(\displaystyle 800 - 281 + 154 - 165 + 342\)

\(\displaystyle =519 + 154 - 165 + 342\)

\(\displaystyle =673 - 165 + 342\)

\(\displaystyle =508 + 342\)

\(\displaystyle = 850\)

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