To simplify a fraction by dividing both top and bottom by the same amount.
Example: 2/10 can be simplified to 1/5 by dividing both top and bottom by 2, in other words we "cancel by 2" or "reduce by 2".
We can cancel by any value, so long as both top and bottom of the fraction can be divided exactly by it (they must both end up as integers):
Example:
• 6/21 can be simplified to 2/7 by dividing both top and bottom by 3 ("cancel by 3").
• But 5/21 can not be simplified. Try dividing both top and bottom by 2, how does it work out? Try other values like 3, or 5, how do they work out?
In Algebra we can also cancel variables like this:
Example: 3xy/2x can be simplified to 3y/2 by dividing both top and bottom by x
Also called "cancelling out"