Fraction of a number

In this lesson, we will learn:

• How to understand fraction of a number using: models with shapes, models with fraction blocks, and fraction number lines
• The steps for multiplying a fraction with a whole number

Notes:

• When we are looking for a fraction of a number, we are using multiplication
• The word “of” in math usually signifies multiplication


• We can use models with shapes to find the fraction of a number:
• Ex. What is $\frac{1}{5}$ of 15?
• Use 15 circles to represent the whole number; divide into 5 equal parts; answer how many circles are in 1 of those parts:

Therefore, $\frac{1}{5}$ x 15 = 3

• We can also use models with fraction blocks to find the fraction of a number:
• Ex. What is $\frac{2}{3}$ × 5?
• Create a fraction block with 2 of 3 equal parts shaded in. Repeat 5 times.




• There are 10 parts shaded in, each one is worth $\frac{1}{3}$ of a whole.
• Therefore, $\frac{2}{3}$ x 5 = $\frac{10}{3}$ or 3 $\frac{1}{3}$


• We can also use number lines to find the fraction of a number:
• Ex. What is 4 × $\frac{1}{5}$ ?
• Split a line (from 0 to 1) into 5 equal parts, create 4 jumps of 1 part each ($\frac{1}{5}$)

• Generally, the fastest way to find the fraction of a number will be to do fraction multiplication with a whole number using these steps:

Step 1: Put the whole number as a fraction over 1
Step 2: Cross cancel the numbers if possible
Step 3: Multiply the top numbers and then separately multiply the bottom numbers
Step 4: Write your answer in lowest terms
• Ex. What is $\frac{6}{18}$ of 24?