It's time for some mathematics ...

[Calavera]

Ok, I may as well also ask this here at I2. Math experts with good written teaching skills needed!

Say, on a number line, we have units 0 - 5 as follows:

0-1-2-3-4-5

Let's say I want to understand why calculating 5 - 4 = 1 works when finding the distance between 4 and 5 on the number line.

So I imagine that I'm removing 4 unit spaces from the number line (specifically from 0 - 4) so that I'm supposed to be left with a unit space of 1.

But if the number 4 was removed in my imagination, then what should be left seems to be less than a unit space of 1. Or is it still a whole one unit space that's left?

This is what I'm trying to figure out.

[odeon]

You are having boundary issues.

Draw that line and be sure to mark all 6 positions, 0-5. Essentially, if you begin with the mark for 5 and include it when counting backwards to 4, 3, 2 and 1, you can't include the mark immediately before when counting units because that would mean that your single unit was too big. One unit is everything *after* the previous mark and including the current one; in other words, you'd be including a positional indicator twice.

I tried to do a text drawing but realised I need a monospaced font. Can't be arsed to find one so I'll leave you to do it on paper.

[Calavera]

Ok, I'll need some time to process this properly and will be back with you soon to let you know whether or not I get it now.

[Calavera]

Still trying to get there, but someone else was kind enough to make a visual representation for me to consider.

Could this confusion be related to me failing to grasp that the "point" is zero-dimensional?

[odeon]

I suppose it could.

Studying a ruler carefully should also do the trick.