Lesson 11 of 15
A dot that is not a decimal point
Show on a big screenA film runs for 2.4 hours. Is that 2 hours 40 minutes?
Loading lab…
Step 1 of 4
- A clock face is one hour. The hand starts at the top.
- Cut the hour into ten equal parts. Each is 0.1.
- One tenth is 60 ÷ 10 = 6 minutes.
- Four tenths is 4 × 6 = 24 minutes.
The rule
No. 2.4 hours is 2 hours 24 minutes. We write h for hours and min for minutes.
A tenth of an hour is 6 minutes. So 0.4 h is 4 × 6 = 24 min. And 2.4 h is 2 h 24 min.
In cricket, an over has 6 balls bowled. A foot has 12 inches. We write ft for foot and in for inches. A ball is not a tenth of an over. An inch is not a tenth of a foot.
So some dots are not decimal points. A score board writes 7 overs and 3 balls as 7.3. As a decimal, 3 balls is 3 ÷ 6 = 0.5 over. So it is 7.5 overs.
| Reading | Small part | Divide by | As a decimal |
|---|---|---|---|
| 2 h 24 min | 24 min | 60 | 2.4 h |
| 7 overs 3 balls | 3 balls | 6 | 7.5 overs |
| 3 ft 3 in | 3 in | 12 | 3.25 ft |
Try the lab to finish this lesson.