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1. Radio buttons (small circles with numbers or text next to them): Click on the appropriate radio button. To change your answer, click on a different botton. To "erase" your choice and start over, you need to open some other page.
2. Pull-down menu: Click-and-hold on the blue box with up/down arrows, move to the answer you want, and release the mouse button.
3. Number boxes: If there is no additional grey box below the answer box, you can enter a number or a numerical formula, for example (1/2) * 9.81 * 2.5^(-2) , with **no blank spaces** and ** and no letters ** for units. The number is assumed to be in the units listed in the question text. Note that you can also use scientific notation, for example 6.67*10^(-11), but **note ** the use of () for the exponent! The system also recognizes "pi". The computer grading algorithm does not know about significant figures so you don't need to worry. Make sure to include enough that your answer is correct to a few %. Note that in many cases, combining two answers which are correct to the required precision (~few %) ** will not ** necessarily give a new answer to the required precision (for example, subtracting two big numbers to get one small one).
Do not use a comma for decimals, use a full stop - 3.142, not 3,142
4. Formula boxes: If there is an additional grey box below the answer box, the program might expect a formula or it *might* expect a number, for example 0. Type in the formula for the answer. The system also recognizes "pi". The grey box underneath the answer box will show how the program is interpreting what you have typed. There is more information on how to correctly type in formulas [here](#Syntax).
5. Drag and drop: If you see a formula with things missing and options to fill the missing pieces below, simply drag the correct pieces into place to input your answer.

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You do this by clicking the "Check" or "Final Check" button. **

Warning:**  You must *enter* your enter your responses to **all** of all of the sub-questions **first** before *submitting* first, before submitting your answer (but see the next topic for exceptions to this rule).

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* Invalid input: Could not parse BlahBlahBlah as a formula: This means that there is a mathematical error in your entry. Perhaps you did not match your parentheses () correctly. Look ** very ** carefully at what appears in the grey box underneath your answer to see if it looks correct.

How can I see the right answers?

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