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A Story of Numbers

Where a digit sits decides what it is worth

The digits 2, 0 and 5 can write 205. They can also write 502. The two numbers differ by 297. A digit is one of 0 to 9. Why do the same digits make two numbers?

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Three columns: hundreds, tens, ones.
Step 1 of 4
  1. Three columns: hundreds, tens, ones.
  2. A 5 in the ones is worth 5.
  3. The same 5 in the tens is worth 50.
  4. The same 5 in the hundreds is worth 500.

Each digit is worth what its column says. A column is the place for one digit. The ones column is worth 1. The tens column is worth 10. The hundreds column is worth 100.

Rule: Each column is worth ten of the column on its right. The digit stays the same.

So 205 is 2 hundreds and 5 ones. That is 200 + 0 + 5.

2, 0 and 5, rearranged
ArrangementWorthNumber
2052×100 + 0×10 + 5×1205
5025×100 + 0×10 + 2×1502

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This track

  1. 0 Start here
  2. 1 One mark for one thing
  3. 2 Marks in bundles can be read at a glance
  4. 3 A number as the total of its symbols
  5. 4 Where a digit sits decides what it is worth
  6. 5 A mark for an empty place
  7. 6 Ten symbols will write any whole number
  8. 7 The same sum, worked out two ways
  9. 8 One number, several ways of writing it
  10. 9 The big picture
  11. 10 Track quiz

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