Math Homework Help

Mysterious Number 1089

November 8th, 2006 . by Vanaja

1. Think of a 3 digit number where all the digits are different.
2. Reverse the digits
3. Subtract the smaller number from the larger number
4. Reverse the digits again
5. Add the numbers in steps 3 and 4

Whatever 3 digit number you choose the number will always be 1089!

Here is an example

1. 543
2. 345
3. 543 - 345 = 198
4. 891
5. 891 +198 =1089

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 4 Responses to “Mysterious Number 1089”

1. comment number 1 by: Anonymous
   November 8th, 2006 at 5:02 pm
   

   My number= 291

   1. 291
   2. 192
   3. 291-192=99
   4. 99
   5. 99+99=198

   Busted, sorry.

2. comment number 2 by: Ben
   November 8th, 2006 at 5:17 pm
   

   The numbers have to be 3 digits ie. 99 would be 099 reversed would be 990. 990 + 99 = 1089

3. comment number 3 by: Henry
   November 21st, 2006 at 7:27 pm
   

   1. 321
   2. 123
   3. 123 - 321 = -198
   4. -891
   5. -891 + (-198) = -1089

   which is not 1089

   busted!

4. comment number 4 by: Math
   November 22nd, 2006 at 7:29 am
   

   Dear Henry,
   I think you didn’t read the third step correctly.It is “Subtract the smaller number from the larger number”. So in your example it is 321-123 = 198 & not 123 - 321 = -198. So in the end you will get 1089 not -1089.

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