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Math Skills: This trick is good for helping students practice four-digit subtraction.
What You Need: Piece of paper and pencil
Performing the Math Trick
- Have someone choose any four-digit number. (At least one digit should be different from the other digits)
- Arrange the digits in order from largest to smallest and write that number down.
- The person chooses the number 4,081
- Rearrange digits in order from largest to smallest:
- Now have them reverse the digits of this number and subtract it from the last number they wrote down.
- After they subtract and get the answer, have them arrange the numbers from greatest to least if they are not already.
- Now have them subtract the reverse of this number from itself (same procedure as above).
- Keep repeating these same steps and they will soon arrive at the magic number: 6174!
Not at the Magic Number yet, so they keep going.
And just like magic…..they will reach the Magic Number! (See below)
Pretty Cool! It works every time.
Note: It might be a good idea to make sure they are doing the subtractions correctly, otherwise they may not get to the Magic Number.