ERR:SYNTAX is the TI-84's way of saying it couldn't parse what you typed — somewhere in your expression there's a character the calculator doesn't understand in that position. The good news: this is the easiest error to fix, because the calculator will show you exactly where the problem is. Here's how to find it and the mistakes that cause it most often.
The fastest fix: let the calculator find it
When the error screen appears, you get two options: 1: Quit and 2: Goto.
- Choose
2: Gotoand the cursor jumps straight to the offending character in your expression. - Look at what's under (and right before) the cursor — that's your problem spot.
- Fix that character, press
ENTER, and you're done.
Don't pick 1: Quit unless you want to abandon the line entirely. 2: Goto does the detective work for you.
The #1 cause: negative sign vs. subtraction
The TI-84 has two different minus keys, and mixing them up is the single most common reason students see ERR:SYNTAX.
| Key | Looks like | What it's for | Where it is |
|---|---|---|---|
(-) | small, raised ⁻ | Making a number negative | Bottom row, left of ENTER |
− | full-size dash | Subtracting one thing from another | Right column, above + |
The rule of thumb:
- If the minus comes between two numbers, use the subtraction key
−. Example:5 − 3. - If the minus comes at the start of a number (or right after
(,=,*,/, or another operator), use the negative key(-). Example:(-)4 + 7, orY1 = (-)2X.
Typing subtraction where a negative sign belongs — like starting a line with the big − key — is what trips up most people. If your expression begins with a minus, or you're entering a negative number after an operator, it must be (-).
Other common causes
If the cursor doesn't land on a minus sign, check for these:
- Missing closing parenthesis. Every
(needs a matching). Count them, especially in nested expressions like((3+2)*(4−1). - Two operators in a row. Something like
5 + * 3or2 − / 4can't be parsed. Delete the extra operator. - Starting an expression with an operator. A line that begins with
+,*,/, or the subtraction−is invalid. (Starting with(-)for a negative number is fine.) - Implied multiplication mistakes. Writing things like
2(3and forgetting to close, or jamming symbols together in a way the calculator can't interpret. When in doubt, type the multiplication sign explicitly:2*(3+1). - Letters where a command belongs. If you typed
S,I,Nas three separate letters instead of pressing theSINkey, the calculator sees three variables, not a function. Always use the actual function keys or menus.
A quick checklist when Goto lands somewhere confusing
Sometimes the cursor lands one character after the real mistake, because that's where the parse broke. Scan a few characters to the left and ask:
- Is every
(closed with a)? - Is every minus the right kind —
(-)for negatives,−for subtraction? - Are there two operators touching each other?
- Did I spell out a command letter-by-letter instead of using its key or menu?
Fix one thing at a time and press ENTER again. If a different error appears (like ERR:DOMAIN or ERR:DIM MISMATCH), that's progress — your syntax is fixed and it's a different issue now. See the full rundown of TI-84 errors in /error-fixes/error-messages/.
Try the fix right now
Don't have your calculator handy, or want to test without messing up your work? Open the free online TI-84 calculator — it runs right in your browser with no download. Type −5 + 3 using the subtraction key, watch ERR:SYNTAX appear, choose 2: Goto, and swap in the (-) key. Once you've seen it once, you'll never mix them up again.