Missing Operations

A Mathematics Lesson Starter of the Day from a Winter Wonderland

(38  31)  33 = 36

33  (24  32) = 801

(34  22)  28 = 776

(39  23)  (33  38) = -80

Which operation (plus, minus, times or divide)
does each red box represent?

Topics: Starter | Xmas

You can find many more ChristMaths activities at:



  • Dave Loboda, St John's Middle School, Bromsgrove
  • Have used a number of your starters and found them to be very useful and enjoyable. We used the problem for 9 December today and one of the pupils pointed out what he felt was an error in the solution.

    You gave 24 + (39 + 36) x 36 = 3564 it was pointed out that, using BIDMAS strictly, you should complete the brackets first, then multiply by 36 before adding the 24 at the start which will give 2724

    Thank you
  • Transum,
  • Thanks Dave. It is very good of you to take time to point out the error. The numbers and operations in this starter are generated randomly each time the page is refreshed. The combination of randomly generated operations you came across was handled incorrectly by the software. The problem has now hopefully been solved.
  • Franziska Fisken, Telford
  • I used this activity and found it a useful intro to BIDMAS /BODMAS!
  • Liz Richards, Lambeth College
  • When will Maths teachers realise that bidmas/bodmas does not always work?
  • Nairn Spink, High School Of Dundee
  • Hello transum,the class enjoyed this starter.we will definetly come back and do more activities. We were very happy when we got the answers.
  • Mary Tonti, Cleveland, OH
  • This is the second time to your site. I am getting ready to go back to school soon and althought we are not in school right now, I can see how this would get the kids to experiment with the different operations.
  • Paul Harris, Chalfont St Peter
  • Liz, coming at this from a Mathematician AND a maths teacher, what do you mean?
    BIDMAS/BODMAS is not some phrase that Maths teachers have invented to try and answer questions in Maths, it is the order of operations which happens, dictated by the constructs on which Mathematics is built. Brackets are computed first, then powers, then Multiplication/Division, computed in order of encounter from left to right, and finally Addition/Subtraction from left to right. I am always open to being wrong but as far as I know, BIDMAS is always going to hold as it is principle which underpins computation. Can you provide a counter example?
  • M Shepherd, The St Lawrence Academy
  • When will people realise that BODMAS / BIDMAS doesn't work?
    (comment from previous post)
    Yes it does, but you don't write it as six consecutive letters, you write B then O then D on top of M and then A on top of S.
    This reminds classes that divide & multiply and add & subtract happen simultaneously, and should therefore be done in the order they appear.
    This avoids the confusion of 10 - 3 + 2 equaling 5 instead of 9, for example.
    Anyone still teaching BODMAS as a six letter word should think on this...
  • Vikram,
  • This really helped me in my learning!!!

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.

Previous Day | This starter is for 9 December | Next Day



Sign in to your Transum subscription account to see the answers

Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.

Note that the interactive student version would be better if your students have access to technology.

There is a printable worksheet to go with this activity.


Your access to the majority of the Transum resources continues to be free but you can help support the continued growth of the website by doing your Amazon shopping using the links on this page. Below is an Amazon link. As an Amazon Associate I earn a small amount from qualifying purchases which helps pay for the upkeep of this website.

Educational Technology on Amazon


Online Maths Shop

Laptops In Lessons

Teacher, do your students have access to computers such as tablets, iPads or Laptops?  This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments:


However it would be better to assign one of the student interactive activities below.

Laptops In Lessons

Here is the URL which will take them to a structured online missing operations exercise.


Student Activity

Here is the URL which will take them to an exercise on the order of operations which is a prerequisite skill:


Student Activity

BIDMAS is an acronym reminding students of the order of operation used when evaluating expressions involving a number of different operations. The letters of BIDMAS stand for:

When only addition and subtraction (or only multiplication and division) are left in an expression work them out in the order you find them, starting from the left and working towards the right.

Curriculum Reference

See the National Curriculum page for links to related online activities and resources.


©1997-2024 WWW.TRANSUM.ORG