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The Addition and Subtraction Rule

This program is designed to give you practice in using the rule for finding the number of significant digits in the sum or difference of numbers. In the program, sets of decimal numbers are randomly generated - and you have to convert to work out their sum and enter the answer in an answer box. Your answer may be given in decimal, or scientific notation. You can switch between formats by clicking on the 'Sci/Dec' button. This causes the relevant answer boxes to appear on the screen. It does not change your decimal answer into scientific notation for you. You can use the program to give yourself a simple test. See how many of the exercises you can complete correctly by using the Scoreboard. The 'Restart' button clears any existing score and starts you with a new series of exercises. Try out the program here - it should have appeared by now in the area below. Just click on the graphic for the item you want ... or use the links on the left

About the buttons that you will see in the program window ...

The 'New' button - generates a new exercise The 'Judge' button - click this to have your answer checked The 'Sci/Dec' button - click this to change the answer boxes to accept a number in scientific notation

The 'Restart' button - clears the scoreboard and starts a new series of exercises The 'Text' and 'Hide Text' buttons - these show and hide the Text window The 'Clear' button - resets the answer box(es)

The 'Peek' button - lets you see the answer expected by the program, along with some information on how it was obtained The 'Quit Practice' button - not active in this demo, it would return you to the CheMentor main menu The 'Activities Menu' button - not active in this demo, it would return you to the menu for the module

Link to the other modules ...