#1 I’m So Rich That I Can’t Even Collect All of My Coins
To get use of excess gold coins and get to where you can start collecting those residence taxes…
At the top of the screen near the area where you can edit your city title, there is a bar with ten slots for built up Knowledge Points. At the right end of the bar is a green plus (+) sign. If you click on this plus sign a window will pop up which allows you to spend coins, boosted goods and diamonds to purchase Knowledge Points.
Each time you buy a Knowledge Point, the cost for the next purchase will increase in that currency. Using coins will make the next coin purchase more expensive, using goods will make the next purchase using that specific good more expensive, etc…
Be careful when gaining your tenth knowledge point. You will lose any progress on the timer as soon as you gain the dreaded tenth point and so it is a good idea to use your points in the research tree (or Ancient Wonders) as soon as you get to nine points.
Another way to use excess coins is to go into the Trader and head into the Wholesaler tab. In the Wholesaler you can use coins to buy up non-boosted goods. This is also one of the only ways to use excess Supplies that you may have when you can’t collect from Workshops.