When it comes to doing subtraction problems like this in your head, I suspect that most people who excel at this type of mental math use a method similar to the number line diagram that is shown ...

Traditional descriptions of math diagrams benefit from descriptions that are brief and specific. Organize the description in a linear fashion, in this case, moving left to right and use bullet points ...

Venn used the diagrams to prove a form of logical statement known as a categorical syllogism. This can be used to model reasoning. Here’s an example: “All computers need power.