Concept 3 of 6
The Odd Number
Today's big idea
Find the number that breaks the rule
Even, in 5s, in 10s — one won't fit.
How it works
👀 What's going on?
Numbers can be sorted too. 2, 4, 6, 7 — three of those feel like they belong together and one sits apart, because three are even and 7 is odd.
💡 Here's the trick
Look at the four numbers above. Three of them share a rule — they might all be even, or all end in 0, or all be counted in 5s. The odd number is the one that breaks the rule.
- 1.Look at the four numbers.
- 2.Find a rule that three of them follow (even, or in 5s, or in 10s).
- 3.The number that breaks that rule is the odd one.
✍️ Try it
- 1.3, 5, 7, 8 — which is odd?
- 2.12, 14, 15, 16 — which is odd?
Set 1 is three odd numbers and one even (8). Set 2 is three even numbers and one odd (15).
⚠️ Watch out
Try more than one rule before you decide. If even does not split them, try 'ends in 0' or 'counted in 5s'. The right rule leaves exactly one number out.
See it in action
⚡ Time to play!
Three numbers follow one rule. Tap the number that breaks it.
ODD ONE OUT · ROUND 1 OF 3
Which number does not belong?
Quick check
✅ VERIFICATION
Which number is the odd one out? Tap it.
⚡ Finish the activity above first to answer.
Keep going!
Up next: Grouping
Match the group's rule to join it.