Calculator error messages explained
What each error message means on your calculator, what usually causes it in an IGCSE Maths question, and how to fix it. The meanings and fixes come from the manufacturers' own manuals and help pages.
Casio fx-991EX ClassWiz
Why does my fx-991EX say Math ERROR?
A result, or a value you typed, is outside the range the calculator can handle, or you asked for something mathematically impossible, such as dividing by zero.
What to check first: Look for a zero denominator, sin⁻¹ or cos⁻¹ of a number bigger than 1 (often a wrong side or angle in the sine or cosine rule), the log of 0 or of a negative number, and a value stored in a variable earlier that you forgot about.
How to fix it: Casio's advice: check the values you typed, use fewer digits and try again. If a variable is the input to a function, make sure its value is one the function accepts.
Source: Casio fx-991EX / fx-570EX User's Guide (PDF): Error messages
Why does my fx-991EX say Syntax ERROR?
There is a problem with the format of the calculation. In Matrix and Vector calculations it also appears when the sizes do not suit the operation.
What to check first: A missing or extra bracket, or two operation signs in a row. With matrices or vectors: adding a 2 × 2 to a 3 × 3, or a product whose sizes do not match.
How to fix it: Casio's advice: make the corrections. For matrices and vectors, check the size you set for each one.
Source: Casio fx-991EX / fx-570EX User's Guide (PDF): Error messages
Why does my fx-991EX say Stack ERROR?
The calculation is too long or too deeply nested for the calculator's working memory (its number and command stacks).
What to check first: Usually one very long expression typed in one go, with brackets inside brackets.
How to fix it: Casio's advice: simplify the expression or split it into two or more parts.
Source: Casio fx-991EX / fx-570EX User's Guide (PDF): Error messages
Why does my fx-991EX say Can't Solve?
SOLVE could not find a solution.
What to check first: A typing slip in the equation, or a start value far from the root you want.
How to fix it: Casio's advice: check the equation for mistakes, then give a start value close to the solution you expect.
Source: Casio fx-991EX / fx-570EX User's Guide (PDF): Error messages
Why does my fx-991EX say Time Out?
A derivative or integral calculation ended without meeting its ending condition.
What to check first: An integral of a function that changes very quickly, or over a very wide interval.
How to fix it: Casio's advice: increase the tol (tolerance) value. The answer is then less precise.
Source: Casio fx-991EX / fx-570EX User's Guide (PDF): Error messages
Casio fx-991CW ClassWiz
Why does my fx-991CW say Math ERROR?
A result, or a value you typed, is outside the range the calculator can handle, or you asked for something mathematically impossible, such as dividing by zero.
What to check first: Look for a zero denominator, sin⁻¹ or cos⁻¹ of a number bigger than 1 (often a wrong side or angle in the sine or cosine rule), the log of 0 or of a negative number, and a value stored in a variable earlier that you forgot about.
How to fix it: Casio's advice: check the values you typed, use fewer digits and try again. If a variable is the input to a function, make sure its value is one the function accepts.
Source: Casio fx-991CW / fx-570CW User's Guide: Errors
Why does my fx-991CW say Syntax ERROR?
There is a problem with the format of the calculation: it is typed in a form the calculator cannot read.
What to check first: A missing or extra bracket, two operation signs in a row, or a function with nothing after it.
How to fix it: Casio's advice: make the corrections and try again.
Source: Casio fx-991CW / fx-570CW User's Guide: Errors
Why does my fx-991CW say Stack ERROR?
The calculation is too long or too deeply nested for the calculator's working memory (its number and command stacks).
What to check first: Usually one very long expression typed in one go, with brackets inside brackets.
How to fix it: Casio's advice: simplify the expression or split it into two or more parts.
Source: Casio fx-991CW / fx-570CW User's Guide: Errors
Why does my fx-991CW say Argument ERROR?
There is a problem with an argument: one of the inputs the calculation uses.
What to check first: A function given the wrong kind of input.
How to fix it: Casio's advice: correct the argument.
Casio fx-CG50
Why does my fx-CG50 say Ma ERROR?
Casio's Math ERROR: the result is outside the allowable calculation range, or you are trying to do an illegal mathematical operation, such as dividing by zero.
What to check first: Look for a zero denominator, sin⁻¹ or cos⁻¹ of a number bigger than 1 (often a wrong side or angle in the sine or cosine rule), the log of 0 or of a negative number, and a value stored in a variable earlier that you forgot about.
How to fix it: Casio's advice: check your input values and change them so the result is within the allowable range.
TI-84 Plus CE
Why does my TI-84 Plus CE say ERR:DOMAIN?
A value given to a function or instruction is outside the values it accepts. In a regression, TI says it means the data do not suit the model you chose.
What to check first: Is every input allowed? σ must be positive, p between 0 and 1, and sin⁻¹ or cos⁻¹ needs a number from −1 to 1. Exponential and power models need positive data.
How to fix it: Change the value that is out of range, or choose a model that suits the data.
Source: TI-84 Plus CE Reference Guide: Error messages · TI knowledge base 34423: ERR:DOMAIN in a regression
Why does my TI-84 Plus CE say ERR:DIM MISMATCH?
Lists or matrices in the same operation have different sizes (TI's example: multiplying two lists with different numbers of elements).
What to check first: L1 and L2 with different numbers of values (one value missed or typed twice), a frequency list of the wrong length, or matrices whose sizes cannot be multiplied.
How to fix it: Make the lists the same length, or check the size of each matrix.
Source: TI-84 Plus CE Reference Guide: Error messages · TI knowledge base 34573: ERR:INVALID DIM or ERR:DIM MISMATCH
Why does my TI-84 Plus CE say ERR:INVALID DIM?
TI's knowledge base: one or more stat plots are turned on, but the lists they use are empty.
What to check first: A stat plot left on from a statistics question, so the error appears when you graph a function.
How to fix it: Turn off the stat plots you are not using, or put the data back in the lists.
Source: TI knowledge base 34573: ERR:INVALID DIM or ERR:DIM MISMATCH
Why does my TI-84 Plus CE say ERR:SYNTAX?
The command contains a syntax error: a misplaced function, argument, bracket or comma.
What to check first: TI points out that subtract − and negative (−) are different keys, and using the wrong one causes this error. Then check the brackets and commas.
How to fix it: Find the misplaced function, argument, bracket or comma and correct it.
Source: TI-84 Plus CE Reference Guide: Error messages · TI knowledge base 40403: syntax error with negative numbers
Why does my TI-84 Plus CE say ERR:ARGUMENT?
A function or instruction does not have the correct number of arguments (inputs).
What to check first: A distribution command with an input missing: normalcdf( needs lower, upper, μ and σ.
How to fix it: Give every argument, separated by commas.
Source: TI-84 Plus CE Reference Guide: Error messages
Why does my TI-84 Plus CE say ERR:STAT?
A statistics calculation was tried on lists that are not suitable. A statistical analysis needs at least two data points.
What to check first: An empty or one-value list, or the wrong list named in the command.
How to fix it: Check the lists named in the command and the data in them.
Source: TI-84 Plus CE Reference Guide: Error messages
Why does my TI-84 Plus CE say NONREAL ANSWERS?
In Real mode, the calculation gave a complex result.
What to check first: The square root of a negative number, or an equation with no real solution.
How to fix it: If a complex answer is expected, switch the mode to a+bi; otherwise check the inputs.
Source: TI-84 Plus CE Reference Guide: Error messages
Why does my TI-84 Plus CE say ERR:DATA TYPE?
An argument is the wrong type, such as a complex number where a real number is needed, or a matrix stored to a list.
What to check first: A complex result used in a real-only command, or a list and a matrix mixed up.
How to fix it: Use the type the command expects.
TI-Nspire CX II
Why does my TI-Nspire CX II say Domain error?
An argument must be in a specified domain, and this one is not (TI's example: rand(0)).
What to check first: Is every input allowed? σ must be positive, p between 0 and 1, and sin⁻¹ or cos⁻¹ needs a number from −1 to 1.
How to fix it: Change the value that is out of range.
Source: TI-Nspire Reference Guide: Error codes and messages
Why does my TI-Nspire CX II say Dimension mismatch?
Two or more arguments must have the same dimension and do not (TI's example: [1,2]+[1,2,3]).
What to check first: Lists of different lengths in a statistics command, or vectors or matrices of different sizes.
How to fix it: Make the lists, vectors or matrices the sizes the operation needs.
Source: TI-Nspire Reference Guide: Error codes and messages
Why does my TI-Nspire CX II say Syntax error?
The syntax checker found a problem.
What to check first: A missing bracket or comma.
How to fix it: Correct the expression and try again.
Source: TI-Nspire Reference Guide: Error codes and messages
Why does my TI-Nspire CX II say Too few arguments / Too many arguments?
The function or command was given fewer (or more) arguments than it needs.
What to check first: A distribution or statistics command with a value missing or an extra comma.
How to fix it: Give exactly the arguments the command needs.
More calculator help
Each guide has its own "If you get an error" section with the messages that come up for that skill:
What else is free here
- IGCSE revision notesEvery Edexcel 4MA1 sub-topic in plain English, with a worked example.
- Past papers and mark schemesLinks to the boards' own papers, with a timer and topic practice.
- Formula sheets (PDF)Edexcel 4MA1 and Cambridge 0580 on one page each, marking what the exam paper gives you.
- Where students lose marksA summary of the examiners' published reports, so you avoid the common slips.
Save your scores and practise the questions that use thisA free account remembers the questions you have done and brings you back to this page.
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Sources
- Casio fx-991EX / fx-570EX User's Guide (PDF): Error messages
- Casio fx-991CW / fx-570CW User's Guide: Errors
- Casio Education FAQ (Ma ERROR / Math ERROR)
- TI-84 Plus CE Reference Guide: Error messages
- TI knowledge base 34423: ERR:DOMAIN in a regression
- TI knowledge base 34573: ERR:INVALID DIM or ERR:DIM MISMATCH
- TI knowledge base 40403: syntax error with negative numbers
- TI-Nspire Reference Guide: Error codes and messages
"What to check first" is our own revision advice. Error wording can differ slightly between operating-system versions: if your screen shows something different, the manual for your version is the reference.