Clock Arithmetic on a 9-hour clock

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There is a fairly fast shortcut to find the standard names for numbers on a 9-hour clock. Can you find it?

Answers.

Try these problems on a 9-hour clock.

  1. 7 + 5
  2. 6 + 6
  3. 11 + 11
  4. 11 + 11 + 11 + 11 + 11
  5. 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7 + 7
  6. -11 + 7
  7. 48 - 22
  8. 1 - 9
  9. -6 - 6
Answers.

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