Concept 2 of 6
Pattern Completion: Find the Missing Piece
Today's big idea
The shortest group that repeats is the core, and it fills in every slot for you.
Counting the core length turns slot 100 from guesswork into arithmetic.
How it works
👀 What's going on?
The floor of your school corridor probably runs tile, tile, dark tile, over and over. Once you have seen three tiles you can call every tile to the end of the corridor. A repeating pattern hands you that power.
💡 Here's the trick
Look at the strip above. The first three items, 🔴 🔵 🟢, are the whole pattern. Everything after them is that little group played again. The smallest repeating group is the core, and it decides what sits in every slot.
🪄 How to do it
- 1.Read along the strip above until the items start over. That group is the core.
- 2.Count how long the core is, then number the slots.
- 3.Work out which place in the core the empty slot lands on.
✍️ Try it
- 1.Pattern 🐝 🐞 🐝 🐞 🐝 🐞 ? What belongs in slot 7?
- 2.Pattern 🌧️ ☀️ ☀️ 🌧️ ☀️ ☀️ 🌧️ ☀️ ? What belongs in slot 9?
Pattern 1 has a core of 🐝 🐞, just two items long. Slot 7 is odd, so it copies slot 1: 🐝. Pattern 2 has a core of 🌧️ ☀️ ☀️, three items long. Slot 9 is 3 + 3 + 3, so it lands on the last item of a core: ☀️.
⚠️ Watch out
You might be thinking the core is whatever group you spot first, and it is easy to stop there. In 🟥 🟥 🟦 🟥 🟥 🟦, some children call 🟥 🟥 🟦 🟥 the core. Play that group again and notice that the strip comes out wrong. Always take the shortest group that rebuilds the strip exactly.
🌟 Why this matters
Repeating patterns run through bead necklaces, floor tiles, drum beats and the stripes on a jumper. Find the core and you can carry any of them on for as long as you like. It is also how you work out which day of the week your birthday lands on.
Exam tip: Pattern questions usually open the reasoning section, so bank them quickly and keep your minutes for later items.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Pattern: ⭐ 🌙 ☀️ ⭐ 🌙 ☀️ ⭐ ? What comes next?”
- 1
Find the core
Shortest repeating group = ⭐ 🌙 ☀️. Core length = 3.
- 2
Look at the last filled slot
The slot before the ? is ⭐.
- 3
What comes after ⭐ in the core?
Core is ⭐ → 🌙 → ☀️. After ⭐ comes 🌙.
- 4
Answer ✓
Next = 🌙
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
First tap Show the core (the part that repeats), then tap the tile that comes next.
PATTERN · ROUND 1 OF 3
Quick check
✅ VERIFICATION
A pattern runs 🔺 🔺 🟣 ⬛ 🔺 🔺 🟣 ⬛ 🔺 🔺. How long is its core?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Alphabet Series
+1, +2, or backwards, same step every time.