Even and Odd Numbers
Even numbers divide by 2 with no remainder; odd numbers leave remainder 1.
Key idea
Even numbers divide by 2 with no remainder; odd numbers leave remainder 1.
In depth
Even numbers split into two equal groups with nothing left over: n = 2k. Odd numbers leave exactly one extra: n = 2k + 1. Parity (even or odd) follows predictable rules, so you only need the last digit to decide.
Worked example
Is 3,578 even? The last digit is 8, so yes: 3578 = 2 × 1789. Is 91 odd? 91 = 2×45 + 1, yes.
Formula
Real-world uses
- Splitting players into teams of two
- Checking parity bits in computing
- Pairing socks or seats
Common mistake
Thinking 0 is neither. Zero is even, since 0 = 2 × 0.
How to learn this
- Read the key idea and say it in your own words.
- Work through the worked example, then try a similar problem.
- Use the interactive lesson’s visual and mini-quiz to check the pattern.
Frequently asked questions
What is Even and Odd Numbers?
Even numbers divide by 2 with no remainder; odd numbers leave remainder 1. It is a topic at the beginner level in Arithmetic & Number Sense.
What is the formula for Even and Odd Numbers?
The key formula is n = 2k (even), n = 2k+1 (odd).
Where is Even and Odd Numbers used in real life?
Real-world examples: Splitting players into teams of two; Checking parity bits in computing; Pairing socks or seats.
What should I learn before Even and Odd Numbers?
Make sure you are comfortable with Ordering Numbers, the previous topic in Arithmetic & Number Sense.
What is a common mistake with Even and Odd Numbers?
Thinking 0 is neither. Zero is even, since 0 = 2 × 0.
How can I practise Even and Odd Numbers?
Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.
What comes after Even and Odd Numbers?
Move on to Skip Counting next.
Related beginner topics in Arithmetic & Number Sense
- Counting & Cardinality – Assigning one number word to each object to find how many there are.
- Place Value – The value of a digit depends on its position: ones, tens, hundreds and so on.
- Number Line – A line where numbers are placed in order at equal spacing to compare and add them.
- Comparing Numbers – Use <, > and = to say which number is smaller, larger or equal.
- Ordering Numbers – Arranging numbers from least to greatest or the reverse.
- Skip Counting – Counting forward by a fixed step such as 2s, 5s or 10s; the root of multiplication.