Miscellaneous Tips

 Order of Operations:

Your TI-83 calculator will perform calculations according to the correct order of operations.  This means that you will have to exercise care in entering expressions so that you adhere to the correct order of operations as well!  For example, if you wanted your calculator to evaluate the expression

Correctly evaluated we get 8/8 or 1.    On the calculator you could not type 3+5/2+2*3.  Why?  The calculator will follow the rules for the order of operations, doing the 5/2 and the 2*3 first to get 3+2.5+6 or 11.5...clearly not what we wanted!  Instead, try typing (3+5)/(2+2*3).  Now we get the expected answer of 1.

More on the special problems of fractions below!

Special Problems with Fractions:

You saw in the above example that it is important to use parentheses to keep the numerator of a fraction together and the denominator of a fraction together.  Another rule of thumb with fractions is that when typing a simple fraction, put parentheses around the whole thing.

For example, suppose we wanted to find:

Since this is just the square root of 9, we should get 3.  However, if you simply type 9^1/2 the calculator will give you an answer of 4.5.  Why?  Go back to the order of operations:  the calculator will do exponents first, taking 9^1 to give 9.  Then it will divide the result by 2, giving 4.5.  To do this problem correctly we need to use parentheses as follows:  9^(1/2).

In general, when in doubt it never hurts to surround a fraction with parentheses!

Converting between Fraction and Decimal Forms

Sometimes we get a calculator answer that is a long ugly decimal.  Often we may know or suspect that the decimal corresponds to a fairly simple fraction, but we can't remember what fraction.  The TI-83 can do the conversion for you.

For example, take the fraction 3/11.  To convert to a decimal we simply take 3 divided by 11 on the calculator, giving .2727272727...   Do this on your calculator.   If this were the answer to a calculation, how could we get the fraction back?  Push the black MATH button (left side of calculator) and you will get a list of options.   Option #1 is to change to a fraction!  Push ENTER or type the number 1.  Your calculator display now reads: "Ans"  then an arrow then "Frac" saying it will convert your answer to a fraction.  Push ENTER, and you should get the original fraction, 3/11, back again.

Taking the nth Root of a Number:

Your calculator has a square root button, but how can you get cube roots, fourth roots, etc?  One option is to convert to a fractional exponent: to take the fourth root of 16, type 16^(1/4). You should get an answer of 2.

You can also find the root operation directly on your calculator.  First type in the root you want.  In the case of the above example, type "4".  Then push the black MATH button.  Option #5 allows you to take any root you like, so select this option either by using the arrow keys to move to it and pushing ENTER, or simply by typing the number 5. Then type the 16.  You will get an answer of 2 again.