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A Peek Beyond the Point

A dot that is not a decimal point

A film runs for 2.4 hours. Is that 2 hours 40 minutes?

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A clock face is one hour. The hand starts at the top.
Step 1 of 4
  1. A clock face is one hour. The hand starts at the top.
  2. Cut the hour into ten equal parts. Each is 0.1.
  3. One tenth is 60 ÷ 10 = 6 minutes.
  4. 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.

Turn the small part into a decimal
ReadingSmall partDivide byAs a decimal
2 h 24 min24 min602.4 h
7 overs 3 balls3 balls67.5 overs
3 ft 3 in3 in123.25 ft

Jump to lesson

This track

  1. 0 Start here
  2. 1 One step past the ones column
  3. 2 The splitting does not stop at tenths
  4. 3 What the point separates
  5. 4 An exact spot between two whole numbers
  6. 5 Which of the two is more
  7. 6 Two names for one number
  8. 7 Line up the points, not the ends
  9. 8 Decimals at the shop and on the scale
  10. 9 A whole and a part, in one number
  11. 10 When the top digit is too small
  12. 11 A dot that is not a decimal point
  13. 12 Checkpoint
  14. 13 The big picture
  15. 14 Track quiz

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