Casio Calculator DATA ERROR — What It Means

What it means

Casio DATA ERROR means the statistical data entered is invalid for the calculation being performed — most often because there is no data entered yet, all values are identical (no variance), or a frequency value is zero or negative.
Check the STAT data table for missing entries or invalid frequency values.

Affected Models

Casio fx-991EX / CW
Casio fx-85GT CW
Casio fx-82ES
Casio fx-9750GIII
Casio fx-CG50

Common Causes

Statistical table is empty — no data entered before running a calculation
All x-values are identical — standard deviation and regression cannot be computed
Frequency column (FREQ) contains 0 — a frequency of zero is invalid
Trying to run two-variable statistics with data in only one column
Paired data has unequal numbers of x and y values

How to Fix It

Check the statistics data table.

Press MODE → 2: STAT (or 3 for SD mode depending on model).
Press 1: 1-VAR or your regression type.
The data table should show your entered values.
If the table is blank, no data has been entered yet — type your values and press = after each one.
Check the FREQ column.

If frequency (FREQ) is shown as a column and any entry is 0 or blank, DATA ERROR will occur.
Each data point must have a frequency of 1 or more.
If you do not need frequencies, set all FREQ values to 1.
Check for identical x-values.

If all your x-values are the same (e.g. all entries are 5), the standard deviation is zero and many statistics cannot be computed.
This is mathematically undefined, not a calculator fault.
Ensure your data has variation in x-values.
Verify both columns have equal row counts for 2-VAR statistics.

For two-variable statistics, every x-value must have a corresponding y-value.
If the x column has 5 entries and the y column has 4, you will get DATA ERROR.
Count both columns and ensure they match.
Delete all data and re-enter.

In the STAT editor, move the cursor to the column header (top row), press DEL-A or F3 (Edit) → Delete All.
Re-enter your data values carefully, pressing = after each number.

Frequently Asked Questions

Does Casio DATA ERROR mean my calculator is broken?

No.
DATA ERROR is a user data issue — not a hardware fault.
It means the numbers entered are not valid for the requested statistical operation.
Correct the data and the error will not reappear.

Can I save statistical data on a Casio calculator for later use?

On graphing models (fx-CG50, fx-9750GIII), statistical list data can be saved to named lists and recalled later.
On scientific models (fx-991, fx-85), statistical data is cleared when you exit STAT mode — save important data to memory variables (A–F) before exiting.