If you are familiar with the concept of taking an integral then it is quite similar to this argument. To find the area under a line (or any shape on a graph) you essentially have to take an infinite number of strips under the shape and add each of those areas together to find the overall area.
A lot of these arguments are based around infinity. Another example in mathematics is that if you have an equation of say:
(Infinity+1)/Infinity
What would be the answer?
The answer would still be 1 even though (9+1)/9 does not equal 1. This is because anything added or subtracted to infinity doesn't make a difference. Essentially when you have a REALLY large number such as infinity, all other numbers just don't have any effect on it. That is pretty much the argument.
