TI-84 Error Messages Explained — ERR:SYNTAX, ERR:DOMAIN & More

The TI-84 Plus CE displays cryptic error codes when something goes wrong. Here's what each one means and how to clear it.

How to Clear Any Error

When an error appears, press:

• 2: GOTO — jumps to the exact spot in your expression that caused the error (most useful)
• 1: QUIT — closes the error and returns to the home screen

Always choose GOTO first — it shows you exactly where the problem is.

ERR:SYNTAX

Meaning: The calculator can't parse the expression. There's a typo, a missing parenthesis, or an operator in the wrong place.

Common causes:

• Missing closing parenthesis: sin(45 instead of sin(45)
• Two operators in a row: 3 + × 5
• Using letters as text instead of variable names

Fix: Press GOTO to highlight the problem character. Re-read the expression carefully.

ERR:DOMAIN

Meaning: You passed a value outside the function's allowed range.

Common causes:

• √(-4) — square root of a negative
• log(0) or log(-5) — log of zero or a negative
• sin⁻¹(2) — arcsin only accepts values between −1 and 1

Fix: Check your input values against the function's valid domain.

ERR:WINDOW RANGE

Meaning: Your graph window settings are invalid — usually Xmin ≥ Xmax or Ymin ≥ Ymax.

Fix:

1. Press WINDOW
2. Make sure Xmin < Xmax and Ymin < Ymax
3. Or press ZOOM → 6: ZStandard to reset to defaults

ERR:DIM MISMATCH

Meaning: Two lists or matrices don't have the same dimensions.

Common causes:

• L1 + L2 where L1 has 5 elements and L2 has 4
• A stat plot is enabled with lists of different lengths

Fix: Press STAT → Edit to check list lengths. Make sure all lists used together have identical lengths.

ERR:SINGULAR MAT

Meaning: You're trying to invert a matrix ([A]⁻¹) that has no inverse — its determinant is zero.

Fix: Check your matrix values. A matrix is singular when two rows are proportional or one row is all zeros.

ERR:NONREAL ANS

Meaning: The result is a complex number, and the calculator is in Real mode.

Fix: Either change your input (check for sign errors) or switch to complex mode:

1. Press MODE
2. Select a+bi
3. Press ENTER

ERR:OVERFLOW

Meaning: The result is too large (greater than 9.9999 × 10⁹⁹).

Common causes: Very large factorials (200!), extreme exponents (10^1000).

Fix: Use logarithms for extremely large numbers.

ERR:MEMORY

Meaning: Not enough RAM to complete the operation.

Fix:

1. Press 2ND + MEM → 2: Mem Mgmt/Delete
2. Delete programs or lists you no longer need

Why Does TI-84 Return "1" Instead of an Answer?

This isn't technically an error message, but it's one of the most confusing TI-84 behaviors.

When you type something like 2 = 2 and press ENTER, the calculator returns 1 — because 1 means TRUE (the comparison is correct).

The TI-84 uses:

• 1 = TRUE
• 0 = FALSE

for all comparison operators (=, ≠, >, <, ≥, ≤).

Example:

• 5 > 3 → 1 (true)
• 5 < 3 → 0 (false)
• X = 5 when X = 5 → 1

If you got 1 when you expected a numeric answer, you accidentally used = (comparison) instead of doing a calculation.

This was the cause of one of Reddit's most-commented TI-84 posts — a student lost points on an exam because they didn't realize their "answer" of 1 was actually a comparison result.