# How to colour a mathematical expression to communicate the relative importance of its terms?

In a presentation, I have a mathematical expression, say A+B+C, where:

1. A is the main term, both in magnitude and importance;
2. B is a correction term, much smaller than A, but important nonetheless;
3. C is an error term, smaller than the other two and whose faith is that of being neglected most of the times.

In addition, A has been already introduced elsewhere, whereas B and C are new elements.

I want to choose different colours for the three symbols, or sub-expressions, that visually communicate to the audience the relative importance of those terms, as an integration to the speech. The colours should be readable when projected.

I had started with red for A and gray (dimgray of the SVG colors) for B and C, but this does not differentiate between the last two terms.

Then I thought of using black for A and red for C: red would communicate that C is an error, but unfortunately seems to communicate also that C is more important than A, which I don't want.

Do you have any suggestion?

Edit: I removed the example image because I think that at the end it was a bit misleading on the purpose of this question, which is specifically about the choice of colours, rather than the choice of other elements (e.g. size), or on the opportunity of colouring equations.

• Welcome to GD.SE. Why not just use shades of red? Any specific reason why it needs to be different colors? Can you add an image to better illustrate your problem? Commented Jun 21, 2016 at 11:40
• Would it be possible to share an example of how this will be presented, in context? You say it is a presentation, so is this part of a larger slide with explanations of the terms or a slide on its own or something else?
– Cai
Commented Jun 21, 2016 at 11:42
• @Luciano: Thank you. I'm hesitant in using different shades of the same colour because in my experience they are hardly distinguishable when projected. I'll ad an example shortly. Commented Jun 21, 2016 at 11:48
• @Cai I've added the example, just a portion of the equation. There are no written explanations on the slide. My idea is to corroborate the verbal explanation with colours. Commented Jun 21, 2016 at 11:53
• Is this for screen or print? Commented Jun 21, 2016 at 12:06

Colours are really perceptions, and are affected by other surrounding colours. In a colour you can also play with different characteristics, such as hue, saturation, etc, and in your case also with font weight, font size, etc.

My opinion: I assume you will work over white or very light background.

• The best is to use a neutral grey for symbols (+, /, etc)
• Use red for the error (C), but make it less saturated and more greyish to reduce its importance.
• Use black bold font for the most important piece (A)
• Use a dark grey for (B). In my example below, you can make it slightly lighter if you feel it is important to make it more different from A
• I would not use font size to differentiate the terms
• You don't need to use many colours. This is not the annual Indian festival of colours, so keep your colour game elegant.

Example:

``````(A) #000000
(B) #222222
(C) #d29997
(symbols) #666666
``````
• Thank you! I cannot use bold because bold symbols in mathematics have a special meaning, but I like the idea of black, dark grey and greyish red. I'll give it a try! Commented Jun 21, 2016 at 20:09

Just by looking at your formula I cannot tell what is important and what is not; perhaps before dealing with different colors your should differentiate levels of importance with different sizes.

(forgive me the potato-quality image)

Regardless of the colors used, it is easier to understand that the bigger elements are more important than the smaller ones. This way you can still use colors to separate blocks in your equation.

• OMG. I will adopt this expression! "The potato-quality image!" n_n Commented Jun 21, 2016 at 13:35
• +1, thank you, but see my edit: I'm really interested in the colour choice. Commented Jun 21, 2016 at 15:09