Another way to think about it: for every 100 units in 10, you take 22. That adds up to 2.2.
If your restaurant bill comes to $10, a 22% tip would be $2.2, making your total $12.2. On a 22% off sale, an item originally priced at $10 would be discounted by $2.2, bringing the price to $7.8.
Whether you are calculating a discount, a tax, a tip, or a commission, the math is always the same: multiply 10 by 0.22.