# What Formulas Do You Need to Know for the ACT Math Test Part 1

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Required formulas for the ACT Math Test include ones from algebra, geometry, trigonometry, statistics, probability, graphs, exponentials, logarithms, and sequences.

## Three Types of Central Tendency

There are three different methods to find the central tendency, or average, of a set of values.

**Mean**: sum of all the values divided by the number of values.**Median**: the median is the middle value after ordering values in size order. If there are two middle values, calculate the mean of them.**Mode**: the value that occurs the most often.

The **mean** gives you a value that, if you were to graph all the data, would be somewhere in the middle of all of them. Mean is useful for understanding what score is most likely to happen.

**Medians** help us understand what the middle part of the data looks like. If the data has a lot of high and low values, then the median will be least affected by it.

The **mode** is useful when you want to find out the most common value in a data set.

Use this video lesson to learn more about when and why we use these methods of central tendency and how to calculate the __Mean, Median and Mode__.

## Circle Formulas

it՚s important to memorize and practice these circle formulas:

Circumference:

Area:

Area of a sector:

Arc length:

Where **C** is the circumference, **d** is the diameter, **r** is the radius and is the angle of the sector. The circumference of a circle is the distance around the edge of the circle (the perimeter) .

## Radians

**Radians** are a different way of measuring the angles of a circle. radians equals 360 degrees, or the total number of degrees in a single circle. To convert between radians to degrees:

Go through radians and degrees examples to practice converting between radians and degrees. It is also important to know whether your calculator is in radians or degrees when answering questions using sine, cosine and tangent functions. Learn how to do this in our guide on how to change between radians and degrees on a calculator. You can also check the manual that came with your calculator. Whatever you do, practice switching before your ACT Math test.