Lesson 2 of 11
Marks in bundles can be read at a glance
Show on a big screenA bangle shop counts in packets of twelve, not one by one.
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Step 1 of 4
- Twenty-three marks, no gaps.
- Brackets show four groups of five.
- Four bundles, three loose.
- Check it: 4 × 5 + 3 = 23.
A bundle is a group of marks, all of one size. Loose marks are the ones left over. A packet of 12 bangles is a bundle of size 12.
There are fewer loose marks than the size. Any more would make another bundle.
Rule: Bundles times size, plus the loose marks, give back the count.
Check size 10: 2 × 10 + 3 = 23. Check size 12: 1 × 12 + 11 = 23.
| Group size | Bundles | Loose |
|---|---|---|
| 5 | 4 | 3 |
| 10 | 2 | 3 |
| 12 | 1 | 11 |
Try the lab to finish this lesson.