Being able to make a solid estimate of a percent amount is an important skill.
You'll get problems requiring this with diagrams and numbers, and you need to be practiced and ready to go.
This video shows you different ways of thinking. Get used to applying thinking rather than rote method. What suits your problem to get the best estimate?
Practice exercises are in the Percentages section on letsdomath.ca, or at this link https://88c99a2bb42e4066a1e55efd6...
Do the practice BEFORE looking at my answers sheet! There are notes on there that will look messy unless you've already had a good shot at this for yourself. If you've already done it, the notes will help when you finally look at them.