Data types: real

The idea

In AQA 8525 section 3.2.1, 'real' is one of the data types you must be able to recognise and choose. A real value is a number that can hold a fractional part, so it is stored in floating-point form rather than as a whole number. Contrast it with integer, which stores whole numbers only. For example, a temperature of 36.6 °C, a price of 2.99 or a measurement of 0.75 m all need a real type because the fractional part matters; a count of 12 pupils does not. When a question asks which data type suits a value, decide whether a fraction or decimal point is genuinely needed, then select real. Remember that a value written as 5.0 is still a real because it is stored with a fractional part.

What earns the marks

• Recognises that a real stores numbers with a fractional or decimal part, not just whole numbers.
• Distinguishes real from integer by whether a fractional part is needed for the value.
• Selects real for suitable examples such as a price, a temperature with a decimal, or a measurement.
• Explains that a value such as 5.0 is treated as real because it holds a fractional part.

Common mistakes and how to put them right

• Confusing real with integer.

  Put it right by checking whether the value needs a fractional part; if it does, it is real.

• Assuming any number is an integer.

  Put it right by noting that numbers with a decimal point, such as 2.99, are real.

• Thinking a whole-number-looking value like 5.0 must be an integer.

  Put it right by recognising it is stored with a fractional part and so is real.

Exam tips

• Read the value in the question and ask whether a fraction or decimal point is genuinely needed before choosing real.
• Use a quick contrast in your reasoning: integer for whole counts, real for measured or monetary values with decimals.
• Check option wording carefully, because a distractor may swap real and integer.