Exam-style question
Try this first
Explain why -3, 0, and 5 are integers, but 2.5 is not an integer.
Model answer
What a good answer should say
- -3 is a negative whole number, 0 is explicitly included in ℤ, and 5 is a positive whole number.
- Therefore, all three are integers.
- 2.5 is not an integer because it is not a whole-number value and is not included in the stated set ℤ.
Explanation
Why this works
A complete answer identifies the three parts of ℤ: negative whole numbers, zero, and positive whole numbers. It also distinguishes these from a value with a decimal part such as 2.5.
Common mistake
No common mistake is linked to this question yet.