Broken Calculator

Broken Calculator by Transum.org

A fun activity with some thinking necessary…

Children are asked to click the available keys on the ‘broken’ calculator above to make the numbers 1 – 20. As  each total is achieved the calculation used to achieve a given number will appear in the table on the right.Those who manage to make all twenty totals earn a ‘Transum Trophy’ – a certificate sent to their email (or their teacher’s email if they wish!).


Unlike a normal calculator, for this activity, you cannot use one total you have found to help make another. Each calculation starts from scratch (zero). I also noted that any multiplications are treated as though they are in brackets… they’ll figure it out! Try to make each total using the fewest number of calculator key presses.

Other broken calculators are available from the links within the activity: 1 & 5,  2 & 3,  3 & 4,  4 & 5, 5 $ 2

The activity is tablet friendly and plays well on my elderly iPad mini.


Broken Calculator by Transum.org

Calculation Balance

Calculation Balance by topmarks.co.uk

An excellent site for addition, subtraction, multiplication and division practice. Good for learning your times tables. Also it is a useful tool for teachers to demonstrate balancing simple equations.

Pupils are offered a number of screens with a pair of scales. In one of the pans is a sum or equation. The pupil’s task is to adjust the value in the other pan to make the scales balance.

Includes activities with number bonds, times tables, division facts, sums as words in a variety of different ranges of numbers – within 10, within 20 and tables/division facts in 2x, 3x,4x, 5x and up to 10×10.

This activity is Flash based and is great for desktop computers and interactive whiteboards but may nor work on some mobile devices and tablets

Calculation Balance by topmarks.co.uk