There are also shorter challenges where the goal is to hit the ball through a series of rings or collect a certain number of coins in only a few strokes. (the-games-blog.com)
The coins mined per block is periodically decreased to put an upper bound on the total number of coins ever mined. (money.stackexchange.com)
You may select between 3 and 7 for the maximum number of coins used on the worksheets. (math-aids.com)