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**What’s in this module?**

This module is a quick review of the math skills you will need in clinical calculations. You have done all these problem types in the past, either in college or high school. No advanced math is required.

You’ll be working with decimals and fractions. The operations you’ll be performing are addition, subtraction, multiplication, and division.

Here’s a quick review of some basic math terminology:

https://www.basic-math-explained.com/images/math-terms-divi1.jpg Retrieved 8/15/2019

https://www.basic-math-explained.com/images/math-terms-frac.jpg Retrieved 8/15/2019

https://i.ebayimg.com/images/i/151041134054-0-1/s-l1000.jpg Retrieved 8/15/2019

**Rounding rules to know**

You need to know the rounding rule for numbers less than one ( <1 ), numbers greater than one ( >1 ), trailing zeros, and leading zeros:

- If the answer is less than one (1), take the math out three (3) places past the decimal point (the thousandth position) and round to two (2) places past the decimal point (the hundredth position).
- If the answer is greater than one (1), take the math out two (2) places past the decimal point (the hundredth position) and round to one (1) place past the decimal point (the tenth position).
- Do not include trailing zeros. (Ex: 12.0 mL would simply be expressed as 12 mL and 0.40 mg would be expressed as 0.4 mg)
- Always use a leading zero for numbers less than one. (Ex: .25 mL should be expressed as 0.25 mL)

Please see the **Resources** tab for all your rounding rules. The equivalents you need to know are also in the Resources section.

**Problem Type 1 – Working with Decimal Numbers**

What’s important when you’re working with decimals? You must keep track of the decimal places to have the correct number of places in your answer. Many clinical calculations errors are decimal place errors.

__Multiplication example__ :

Your final answer is 11. Why 11? For answers greater than (>) 1, you are to take the math out to two places past the decimal point and round to one place past the decimal point. In this case, the second place past the decimal point is an 8. Therefore you are to round the first digit up from 9 to 10, which affects the whole number.

__Subtraction example:__

Your answer will round to 1.1 using the rounding rule for numbers >1.

__Division example__:

Your final answer in this problem is 2.5 using the rounding rule for numbers >1.

**Problem Type 2 – Working with Fractions**

In __adding and subtracting__ fractions, use the lowest common denominator to express the fractions.

__Addition example__:

Change 2/3 to 6/9 so that both terms have the same denominator (9).

In __multiplication__, the lowest common denominator is not necessary. Multiply the numerators and the denominators. Then reduce your answer to a mixed number (whole number and fraction) if necessary.

__Multiplication examples__:

This problem requires changing a mixed number (1 2/3) into a fraction (5/3), then changing the answer to a mixed number and reducing the fraction.

__Division __only involves one change. Invert the divisor and multiply as you normally would.

__Division example__:

**Problem Type 2 – Working with Fractions**

Multiplying Fractions

Don't forget your rounding rules.

**Problem Type 2 – Working with Fractions**

Multiplying Fractions