Concept 3 of 8
Odd & Even: The Number Sorter
Today's big idea
Only the last digit decides odd or even; the rest of the number cannot change it.
Ending in 0, 2, 4, 6 or 8 splits evenly; anything else leaves one behind.
How it works
👀 What's going on?
You have 10 sweets and two friends. Five each, done. Now try it with 7 sweets. Somebody ends up holding an extra one, and no amount of shuffling fixes it.
💡 Here's the trick
Look at the sorter above. Only the last digit matters. A number ending in 0, 2, 4, 6 or 8 splits into two equal piles, so it is even. A number ending in 1, 3, 5, 7 or 9 always leaves one behind, so it is odd. The digits in front make no difference at all.
🪄 How to do it
- 1.Cover everything except the last digit, the way the sorter above does.
- 2.If that digit is 0, 2, 4, 6 or 8, the number is even.
- 3.If it is 1, 3, 5, 7 or 9, the number is odd.
✍️ Try it
Is 8,153 even or odd? And what about 2,940?
8,153 ends in 3, so it is odd. 2,940 ends in 0, so it is even. The 8 at the front of one and the 2 at the front of the other changed nothing.
⚠️ Watch out
You might be thinking a big, round-looking number must be even. 2,001 is far bigger than 8, but it ends in 1, so it is odd. Size never decides this. Only the last digit does.
🌟 Why this matters
Sharing sweets, pairing socks, splitting a team in two: you are checking odd or even without calling it that. It is the fastest thing you can know about a number.
Exam tip: Spotting odd or even often kills two wrong options before you calculate anything.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Is 4,872 an odd or even number?”
- 1
Look at the LAST digit only
4,872 — ignore the rest, only the last digit matters. 👀
- 2
Recall the rule
If the last digit is 0, 2, 4, 6, 8 → EVEN. If 1, 3, 5, 7, 9 → ODD.
- 3
Spot which group
The last digit is 2. That's in the even group.
- 4
Answer ✓
4,872 is EVEN
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
How to play:
- Look at the LAST digit of the number.
- Tap the number to pick it up.
- Tap the Odd box or the Even box.
ODD OR EVEN · ROUND 1 OF 2 · SORT ALL 4
Quick check
✅ VERIFICATION
Which of these numbers is odd?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Roman Numbers
I, V, X, L, C, learn the Roman number code.