Weapons of maths construction

You just write what you want. You could write 5 over 9, or write a dash and put 5 on top of it and 9 below, or even write, -59 and then move the 5 and 9 around to their final positions. You can write just as you would on paper and you can edit it freely!

1. If the user wrote 3× =18, the calculator would immediately show the correct missing number, 6, in red so that it is easier to see. Now, here’s our new calculator letting the user change the sum, to one where it is all divided by 5.
2. You can see the user’s wobbly blue handwriting of the division bar and their digit 5. Immediately, the calculator recognises the handwritten 5 and presents it formally as a typeset digit; at the same time it also re-solves the new equation.
3. It gives the answer 30. Now the user might want to edit this by moving the 3×6 to the bottom of the equation, alongside the 5 they wrote earlier. They can select and drag the 3×6 easily.
4. ... and the calculator immediately works out the new answer, 270.