Odd or Even? 🟥🟦
However big the number, one glance at its last digit tells you. Then go further: predict whether a sum or product will be odd or even without working it out.
Loading…
How to play Odd or Even?
- A number, sum or product appears in the box.
- For a single number, look only at the last digit and press Odd or Even.
- For a sum or product, predict the answer's type before working anything out, using the odd/even rules.
- The dots then share the last digit into pairs: an orange dot left over means odd.
- Twelve cases: six numbers, then six sums and products.
The odd and even rules
Even numbers end in 0, 2, 4, 6 or 8 and share into two equal groups; odd numbers end in 1, 3, 5, 7 or 9 and always leave one over. Adding: odd + odd = even, even + even = even, odd + even = odd. Multiplying: odd × odd = odd, and any number × an even number = even. These rules let children check answers quickly: if 357 + 219 comes out odd, something went wrong.
For grown-ups
The first six cases practise the last-digit test on numbers up to six digits. The last six ask for a prediction before any calculating: odd + odd = even, even + odd = odd, even + even = even, odd × odd = odd, and anything × an even number = even. After each answer the dots show the last digit shared into pairs, with any leftover in orange. Ask "why does only the last digit matter?" (every ten shares into pairs). Supports AC9M4N02 in the Australian Curriculum v9.