Understanding Place Value & Rounding Off on TI-15
The TI-15 Explorer isn't just a number cruncher — it's built specifically to help younger students actually see how math works, rather than just handing them an answer. Rounding is a great example: instead of just displaying a shortened number, the calculator lets students set exactly how many decimal places they want, reinforcing what tenths, hundredths, and thousandths actually mean.
Here's the thing to remember: because the TI-15 has function keys built just for this, kids can watch the math happen step by step instead of treating the calculator like a black box.
How to Round a Decimal, Step by Step
- Switch it on. Hit the On/Clear key to get started.
- Enter your number. Type in the full decimal value using the number and decimal point keys.
- Press Fix, then choose a place value. For example, press 2 to round to the hundredths place.
- Press = and read the result. The screen will show your rounded answer, with the Fix indicator active to remind you a place value is set.
The Keys You'll Actually Use
Fix— The star of this guide. It locks the display to a set number of decimal places, so every answer that follows gets rounded consistently.n/d— Not the focus here, but still on the keypad: it separates numerator and denominator when you're working with fractions instead of decimals.Simp— Also unrelated to rounding, but worth knowing: it simplifies fractions, either automatically or manually.
Common Questions
How do I wipe the calculator's memory?
Just tap Clear twice in a row. If that doesn't do it, there's a physical Reset button on the back.
Does the TI-15 simplify fractions on its own?
It can, yes — but it doesn't have to. You can flip between Auto mode (where it reduces automatically) and Manual mode (where you pick the divisor yourself) right from the settings.