Let's review the commands you have learned concerning mathematical operations. Highlight the area next to the word **Answer** to reveal the answer. If there are certain topics you don't feel confident in yet, don't worry. Just go back to the appropriate page and review.

**1**. *True* or *False*: Subtraction is the same as adding a negative number.

**Answer**: True. 5 - 2 = 5 + -2

**2**. Which of the following expressions are equivalent?

- abs(-5)
- -30 / 6
- int(-5.5)
- 5
^{1} - 30 / 5

**Answer**: Choices 1 and 4, which both equal 5.

**3**. *True* or *False*: The complex number *i* squared is equal to one.

**Answer**: False. *i*^{2} = -1

**4**. Evaluate the following expression. Remember the Order of Operations.

**Answer**: The answer is 10. Remember PEMDAS

**5**. Which of the following commands will calculate the number of possible 3 digits number lock codes? The code can use the numbers 0 - 30 and order *does* matter.

- 3 nPr 30
- 30 nCr 3
- 3 nCr 31
- 31 nPr 3

**Answer**: Choice 4. Order matters, making the code a *permutation*. The length of the code, or *r*, is 3 digits, and the number of possible digits. or *n*, is 31, because we can use all numbers from 1 to 30 as well as 0.

**6**. *True* or *False*: The default base of log(n) is 10.

**Answer**: True. To get a different base, use the logBASE function or the formula: log(x)/log(b) = log_{b}(x)

**7**. Which of the following trigonometric identities is correct?

- cos(x) - sin(x) = tan(x)
- tan(x) + cos(x) = sin(x)
- sin(x) / cos(x) = tan(x)
- sin(x) * tan(x) = cos(x)

**Answer**: Choice 3.

**8**. The max() command can be used as a space-saving substitute for which kind of logical operator?

**Answer**: The operator OR. The min() command can be used as a substitute for AND statements.

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