Lesson 7 of 15
Which one does the question want?
Show on a big screenCut ribbons into equal pieces. Or find when two buses leave together. Which one needs the HCF?
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Step 1 of 3
- Ask what the number must do.
- Ribbon: go into both 12 and 18 → HCF = 6.
- Buses: 12 and 18 must go into it → LCM = 36.
One question, asked of the answer
Cutting the ribbons needs the HCF. The buses need the LCM.
Ask what the answer must do. Does it go into both numbers? You need the HCF. Do both numbers go into it? You need the LCM.
| Situation | What the answer must do | Which one |
|---|---|---|
| Cut 12 m and 18 m ribbons into equal pieces | Go into 12 and into 18 | HCF, 6 |
| Buses leave together now, then every 12 and 18 minutes | Have 12 and 18 go into it | LCM, 36 |
| Put 8 and 15 players in equal rows, teams not mixed | Go into 8 and into 15 | HCF, 1 |
| Lamps blink together now, then every 4 and 6 seconds | Have 4 and 6 go into it | LCM, 12 |
Try the lab to finish this lesson.