Calculating the percentage of a number

Source

After the completion of calculating percentage, we are going to look at how to calculate the percentage of a number.

Calculating percentage means we can calculate the marks for a test written.

Calculating the percentage of a number, we can calculate what the percentage of a certain number is.

For example:  What is 15% of 200?

We can follow these steps:

We know that percentage is 100.  We also know that of means to times (x)

• Step 1:  Place the 15 over 1oo.  (15% is 15 over 100)
• Step 2:  Change the of to a times (x)
• Step 3:  Multiply with the number you have to calculate the percentage of, place that specific number over 1 to make it a fraction.  In this case we place 200 over 1.
• Step 4:  Now that you have 2 fractions, we can multiply at the top.
• Step 5:  Multiply at the bottom.
• Step 6:  Divide the answer you get.  (A fraction line is divide)
• Write the final answer.

We can also use the following method for learners who understand and know their time tables:

We can use the first 3 steps as above.

• Step 1:  Place the 15 over 1oo.  (15% is 15 over 100)
• Step 2:  Change the of to a times (x)
• Step 3:  Multiply with the number you have to calculate the percentage of, place that specific number over 1 to make it a fraction.  In this case we place 200 over 1.
• Step 4:  Simplify your answer from top to bottom (numerator to denominator)  In this sum, 100 can go into itself once, and 100 can also go into 200 twice.
• Step 5:  Multiply at the top and bottom with what is left after simplifying.
• The final answer will also be 30.

Learners can see that for both of these sums, the answers will be the same.  It is the same sum, just different methods that were used.  Learners who knows the basics of these sums, will do the longer method and learners who knows their time tables, will do the simplifying method.

Source

We can also write percentages as decimal fractions:

Source

Writing a percentage as a decimal number, we already know that percentage is over 100, so we can just divide with 100.  Dividing by 100 we can also just "move" the decimal point 2 places to the left.

Activities for learners:

Source