Negative sign vs the subtraction key

A classic error: the negative key and the subtraction key are different. Mixing them gives a syntax error or the wrong sign.

In short: The negative sign and the subtraction key are different buttons on a GDC. The negative key, often written (−) or (-), makes a number negative, while the minus key subtracts one value from another. Using the wrong one causes a syntax error or a wrong answer, especially when entering negative values in functions or lists.

When you'd use this

Entering a negative coordinate, parameter or starting value.
Distinguishing 3 − 5 (subtraction) from −5 (a negative number) in the same expression.
A negative number raised to a power, e.g. (−2)³.
Avoiding a syntax error caused by mixing the two keys up.

TI-84 Plus CE Casio fx-CG50 and fx-CG100 TI-Nspire CX

At a glance: TI-84 Plus CE, Casio fx-CG50 and TI-Nspire CX compared

	TI-84 Plus CE	Casio fx-CG50 and fx-CG100	TI-Nspire CX
Key sequence	Use (−) (grey key, bottom row) for a negative number; use − (blue, right column) only between two numbers.	Use (−) for a negative number and − for subtraction; entering −3 needs the (−) key.	Use the (−) key for a negative value and the − key for subtraction - negatives show as a shorter dash.

On a TI-84 Plus CE

Use (−) (grey key, bottom row) for a negative number; use − (blue, right column) only between two numbers.
Example: −5 + 2 needs (−)5 + 2, not −5 + 2.

Tip: A SYNTAX or MA ERROR near a minus sign usually means the wrong key was used.

On a Casio fx-CG50 and fx-CG100

Use (−) for a negative number and − for subtraction; entering −3 needs the (−) key.
Example: −5 + 2 needs (−)5 + 2, not −5 + 2.

Tip: A SYNTAX or MA ERROR near a minus sign usually means the wrong key was used.

On a TI-Nspire CX

Use the (−) key for a negative value and the − key for subtraction - negatives show as a shorter dash.
Example: −5 + 2 needs (−)5 + 2, not −5 + 2.

Tip: A SYNTAX or MA ERROR near a minus sign usually means the wrong key was used.

Related guides

Try it yourself

Here's a real IB-style question that uses exactly this technique.

Easy Calculator Paper 1 [2 marks]

Evaluate −5² + (−2)³.

-33

Mark it

Correct 2 / 2 marks

Worked solution & mark scheme:

M1 −5² = −25 and (−2)³ = −8

A1 -33

Common questions

When would I need to tell the negative sign from the subtraction key in IB Maths?

A classic error: the negative key and the subtraction key are different. Mixing them gives a syntax error or the wrong sign. Entering a negative coordinate, parameter or starting value. Distinguishing 3 − 5 (subtraction) from −5 (a negative number) in the same expression.

How do I tell the negative sign from the subtraction key on a TI-84 Plus CE?

1. Use (−) (grey key, bottom row) for a negative number; use − (blue, right column) only between two numbers. 2. Example: −5 + 2 needs (−)5 + 2, not −5 + 2.

How do I tell the negative sign from the subtraction key on a Casio fx-CG50 and fx-CG100?

1. Use (−) for a negative number and − for subtraction; entering −3 needs the (−) key. 2. Example: −5 + 2 needs (−)5 + 2, not −5 + 2.

How do I tell the negative sign from the subtraction key on a TI-Nspire CX?

1. Use the (−) key for a negative value and the − key for subtraction - negatives show as a shorter dash. 2. Example: −5 + 2 needs (−)5 + 2, not −5 + 2.

What should I watch out for when I tell the negative sign from the subtraction key?

A SYNTAX or MA ERROR near a minus sign usually means the wrong key was used.

How are marks awarded when I tell the negative sign from the subtraction key in an IB exam?

In the worked example on this page (2 marks, Paper 1), the marks are: M1: −5² = −25 and (−2)³ = −8; A1: -33.

Practise with your calculator

Questions that need this technique link back to this guide. Try one in practice mode, or see every GDC guide.