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Lesson 1 of 13

Same digits, new number

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5 min

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Write 3816 in your notebook. Swap the first and last digit. Now the number reads 6813.

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The digits 3, 8, 1, 6 read as 3816.
Step 1 of 4
  1. The digits 3, 8, 1, 6 read as 3816.
  2. Ring the first and last digit.
  3. Swap them. It now reads 6813.
  4. Same 4 digits. A different number.

The rule

Every digit has a place — the spot it has in a number. The places are ones, tens, hundreds and thousands.

Each has its own worth. A 6 in the thousands place is worth 6000. A 6 in the ones place is worth 6.

Move a digit to a new and its worth changes. So the number changes. The digits stay the same.

Example

In 3816 the 3 is in the thousands . The 3 is worth 3000. In 6813 the 6 is in that place. The 6 is worth 6000. 6813 − 3816 = 2997. So the number went up by 2997.

Try the lab to finish this lesson.