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Magic 999 Investigation…


Yesterday you all had a go at one of my favourite Maths problem solving investigations -Magic 999.

Why was this number so special? What was the pattern and did it always work?


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  1. sara Reply

    When you subtract tow diffrent numbers .

  2. sara Reply

    It did not always work for example 342-342=

  3. Freddie Reply

    I found it one of the hardest investigation. : (

  4. reuben Reply

    999 is so magic but it did not always work.

  5. lewkas Reply

    IT WORKED all the time!

  6. Onett Perera Reply

    Magic 999 is magic, extremely magic, however if the two numbers are the same then it refuses to do it’s magic (it will not always work).

  7. Betsy Leach Reply

    it did not work if you take away the same number but if not it allways worked.

  8. Millie :B Reply

    It didn’t always work because if you used 0 as one of your numbers you were subtracting by it didn’t work!

  9. Chelsea Reply

    Magic 999 didn’t work all the time because i think if it ended in a 9 it wont work.

  10. Elle Rigby Reply

    It works for ever number but not two of the same numbers like:

    123-123 dosen’t work

    421-342 does

  11. Luc@s Reply

    I found it quit tricky. It didn’t work because it started with 999 and ended with 999.

  12. Betsy Leach Reply

    You had to think of two three digit numbers and take them away.Then you got the first number and replaced it with 999.After that you take the number wich you replaced with 999,get the anser which you got before and add them together. with the thousand which have take it away and add it to the units. your anser should be the same as the first anser.

  13. Shannon Reply

    It was a very hard puzzle to solve I couldn’t find away when 999
    did not work it was extremely hard so in order to complete the task we had to do lots of working out to complete the task that was set.

  14. ben Reply

    i had a lot of fun and it was very difficult but we worked it out at the end.

  15. stan Reply

    I got confused at first but once you did one you got the hang of it.The way pat used it i did not wok all the time.

  16. Sarah Reply

    it did not always work ,for example 362-362 .

  17. Mani :) Reply

    It didn’t work if you did the same number.

  18. sophia and minnie Reply

    the number was special because it would somtimes eqil the same as the other number by pats method.
    However it only worked if the two numbers added up to 1000 because you take away the 1000 and add it on to the units.

  19. Sophie Reply

    I loved the Magic 999 investigation it was really fun!! The number 999 is Magic because if you do Pats way with the Magic 999 instead of the biggest number and then you do the calculation that he was supposed to do and the answers would be the same!! The pattern was:

    I have the calculation 566-340= Pat wouldn’t do that calculation he would do 999-340= instead 999-340=659 after that he would do 659+566=1225. Then he would get rid of the thousand and make it into one unit then he would add that unit onto the 225+1=226. After that you would do the real calculation which is 566-340=226!

    But it doesn’t always work because if i had 233-233= Pat wouldn’t do that he would do 999-233=766 after that he would do the calculation 766+233-999. After that he would do the real calculation 233-233=0 so they are not always the same answers.

  20. Manon Hollingworth Reply

    It wouldn’t always work because when you had a calculation like 546-103 you would do 999-103=896 and then you would do 896-546=350 but then you would take the thousand away but there is no thousand,so it doesn’t always work.

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