Concept 1 of 9
Tally Marks: Counting in Fives
Today's big idea
Every fifth tally mark lies across the four before it, closing a bundle worth five.
Count the closed bundles in fives, then add the loose marks left over.
How it works
👀 What's going on?
Stand at a school gate counting cars and you cannot stop to write numbers down. So you scratch a mark for each one, and every fifth scratch lies across the four before it.
💡 Here's the trick
Each upright scratch is 1, and the fifth is a diagonal laid across the other four to close the bundle. A closed bundle is always worth 5, and written down it looks like ||||/. A total is the bundles counted in fives, plus the loose marks left at the end.
🪄 How to do it
- 1.Find the closed bundles in the picture above, each one a diagonal across four uprights.
- 2.Count those bundles in fives.
- 3.Add the loose marks that never got a diagonal.
✍️ Try it
What number is ||||/ ||||/ ||| ? And what number is ||||/ ||||/ ||||/ ||| ?
The first is two bundles and three loose marks, so 5 and 5 and 3 makes 13. The second is three bundles and three loose marks, so 15 and 3 makes 18.
⚠️ Watch out
Count bundles, not scratches. A closed bundle holds five marks even though only four of them stand upright, because the diagonal is the fifth. Reading ||||/ as four is what turns 13 into 11.
🌟 Why this matters
Anywhere someone cannot pause to write a number, they are tallying. An umpire keeping score, a shopkeeper counting crates off a van, a bird watcher marking each sighting.
Exam tip: Circle each closed bundle with your pencil before you add, so the loose marks at the end never get counted twice.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Count: |||| |||| (one 5-bundle + 4 loose marks).”
- 1
Count complete bundles
Each closed bundle = 5. One bundle = 5.
- 2
Count loose marks
Loose marks after the bundle: 4.
- 3
Add them
5 + 4 = 9
- 4
Total ✓
Tally = 9
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Tap +1 to draw a tally mark. Every 5 marks become a 5-BUNDLE (four vertical lines + a diagonal).
TARGET · ROUND 1 OF 3
7
Tap +1 exactly 7 times.
Current count: 0
Quick check
✅ VERIFICATION
How would you write 17 in tally marks?
⚡ Finish the activity above first to answer.
Keep going!
Up next: The Tally Table
Bring tally marks together into one tidy table.