lesson

Updated 1 month ago Β· 5 views
Imagine you have 21β of a giant chocolate bar, and a friend gives you 41β of the exact same bar.
How much chocolate do you have in total? You cannot just count two pieces, because the two pieces are completely different sizes!
The bottom number of a fraction is the denominator, and it tells you how many equal pieces make up one whole.
πInteractive diagram
So how can we add these two fractions together when their slices don't match?
Making the Slices Match
Since 4 is a multiple of 2 (2Γ2=4), we can cut each half in half to turn 21β into fourths.
Multiplying both the top and bottom by 2 gives an equivalent fraction: 2Γ21Γ2β=42β.
πInteractive diagram
Notice that we only had to change one fraction, because 4 was already a multiple of 2!
What happens when we try another problem, like 31β+62β?
Worked Example: Sixths and Thirds
Look at the denominators 3 and 6. Because 3Γ2=6, the number 6 is our common denominator.