Concept 6 of 6
Counting in a Line & Clue Ranking
Today's big idea
Count the person once
From both ends: add the two spots, take one away.
How it works
👀 What's going on?
Line up for assembly and you can be counted from the front or from the back — but you only stand in the line once. Some puzzles give you a clue from each end and ask how many are in the whole line; others give a few clues and ask who is tallest.
💡 Here's the trick
If someone is 3rd from the front and 2nd from the back, do NOT just add 3 and 2. They are counted from both ends, so add and take one away: 3 + 2 − 1 = 4 in the line. And when clues say 'A is taller than B, B is taller than C', line them up in order to see who is tallest or shortest.
- 1.For a clue at each end, add the two positions, then subtract 1 (the person was counted twice).
- 2.For in front and behind, add both and add 1 (for the person themselves).
- 3.For taller than clues, write everyone in order — tallest first — and read off the answer.
✍️ Try it
- 1.Meera is 2nd from the front and 3rd from the back. How many are in the line?
- 2.Ravi is taller than Sam; Sam is taller than Tom. Who is tallest? Line 1: 2 + 3 − 1 = 4. Line 2: Ravi > Sam > Tom, so Ravi.
⚠️ Watch out
When a clue counts from both ends, subtracting 1 is what people forget — that person is counted once, not twice. And 'in front + behind' is the other way round: add 1 for the person in the middle.
See it in action
⚡ Time to play!
Picture the line in your head. A person counted from both ends is counted once, not twice.
LINE & RANK · ROUND 1 OF 3
How many children are in the line?
Quick check
✅ VERIFICATION
Sara is 3rd from the left and 3rd from the right in a line. How many children are in the line?
⚡ Finish the activity above first to answer.
Keep going!