[url]mathleague.org[/url] has a Number Sense competition, where every 10 problems is an estimation problem. To help practice estimation, one could try Estimation Golf. [br][br]You can also watch a video about estimation at [url]https://www.khanacademy.org/math/arithmetic/multiplication-division/multi_digit_multiplication/v/multiplying-whole-numbers-and-applications-4[/url][br][br][br]A version of Estimation Golf (see http://mrnussbaum.com/estimationvalley/ or http://users.stlcc.edu/Departments/fvmath/Excellence%20in%20Math%20Contest.htm for other versions).[br][br]You have the option of three types of problems: Linear, Exponential or Rational[br]You have the option of three difficulty levels: Easy, Medium, Hard[br][br][br]You are to enter your guess. The program will keep track of your guesses and whether f(x) is in the appropriate range.[br][br]The result it gives you is whether [b]f(x)[/b] (not x) is too high, too low, or in the appropriate range.[br][br]The first time you run GeoGebra with Java it may take a long time (4-5 minutes) for everything to load.

The object is to guess an x-value that satisfies the inequality in as few attempts (strokes) as possible.[br][br]BUT, only about 2 minutes per stroke are allowed or you get a penalty stroke.