Math 7 - Fractions, Decimals and Percents

This slide show is going to cover:

• Converting Decimals, Fractions, and Percentages into one another
• Adding, Subtracting and Multiplying Decimals
• Long Division w/ Decimals
• PEDMAS with decimals

Also included will be

• Finding the percentage of a number
• Adding sales tax to purchases, discounts, and dealing with word problems

Converting Fractions/Percentages/Decimals

Untitled Slide

Simply put, this chart demonstrates how to convert Fractions, Percentages and Decimals into one another

Say you wanted to convert 0.25 into a percent. You would simply move the decimal two spaces to the right, and at the percentage sign. Ta-da! Now you have 25%

To convert a percentage into a decimal, you would do the exact opposite of what the previous slide instructed.

To make a percentage into a fraction, one would simply take said percentage (25%) and place that number over a denominator of 100.

However, to make a fraction into a percentage, you would have to convert said fraction into a decimal first, if it does not have a denominator of 100.

Converting a decimal into a fraction can be explained in three steps. First, write down the decimal as an improper fraction, with the denominator as one. 0.25 - 25/1.
Then, multiply the numerator and denominator by 10 for every number after the decimal point. If we were to have 25/1, we would multiply 25 by 10 twice, and do the same to the denominator.

To make a fraction into a decimal, you would have to divide the numerator by the denominator. 2/3 as a decimal would be 0.6.

Adding, Subtracting, & Multiplying Decimals

To add two decimals, you just kind of add said decimals normally. It may help to remove the decimal point while adding, to make it simpler. Just remember to put it back on the answer when you're done.

To subtract one decimal from another, simply subtract normally. You can choose to take out the decimal momentarily.

To multiply decimals, just multiply the decimals as you would a whole number.

Alright friends

Long division with decimals is just long division, only with decimals. To do so, you need to know how to do long division.

PEDMAS

PEDMAS Stands For

• Parentheses (Brackets)
• Exponets (Probably won't touch on this topic)
• Division + Multiplication
• Addition and subtraction

Now, PEDMAS is the term used to describe the process in which someone would solve a question like this: "1.5+83x(0.3-0.2)"

Most likely, you will have a calculator on you. To solve such a question, it needs to be done step by step.

First, you'd start with whatever numbers are in brackets. In this case, 0.3-0.2. The answer would be 0.1. Now, going onwards, one would tackle the exponents, of which this question does not include, so we can skip that.

From there, we would tackle any multiplication or division, in the order that they appear. So, we'd do 83 x 0.1, which is 8.3. Now, we do the addition and subtraction in the order that they appear. In this case, the only equation left to solve would be 1.5 + 8.3. That equals 9.8.

Finding the percentage of a number

To find the percentage if a number, you take the number and multiply it so that you have an equivilent fraction with a denominator of 100. For example, if you have 5/25 you need to multiply each number by 4, which gives you 20/100, or 20%. So now we know that 5/25 = 20%

Adding sales taxes to purchases

Adding Sales Taxes to purchases is a fairly simple process. The GST tax is 5% of the original price. To find out what it is, we need to

Discounts

Finding the new price from a discount is a somewhat tedious procedure. Say the original price of an item is 100$, and there is a discount of 60% on it. You would divide 100 by 0.6, giving you 60. Then, subtract 60 from 100 to find the discount, of which in this case is 40.

Word problems including Sales Tax and Discounts.

Word problems that deal with Sales Taxes and Discounts may see confusing at first glance, but when correctly analyzed should not be a problem; as long as one would know how to solve them.

That concludes the presentation