# What does “N” mean and how to count

I've been doing some research around managing our sprint cadence to align teams across time zones and came upon, "N+1" when describing a day of a sprint. I've not been able to find a definition of "N" and how the numbering convention works.

Example: If I wanted our Grooming session to be 2 days before and Sprint Planning to be 1 day before the beginning of a sprint, would I call this "N-2" and "N-1", respectively? And is the first day of the sprint "N0" or would "N0" be the grooming day?

What's a source for this convention (looking for best practice references)? Here's how it was used: Sprint Demo, Retrospective, and Planning sequence with offshore team

• Hi, could you share some links where this nomenclature is used? – Tiago Cardoso Sep 13 '19 at 18:22

For instance, Sprint N+1 Planning the day before Sprint N Demo/Retro would fix my problem, but is probably a bad idea

This is a commonly-used convention (not just in Project Management), where "N" means "some exact number, but for our purposes we don't care exactly which number", while "N+1" means "one larger than that number we were just talking about".

• Fair enough, but what is it saying in the example, then? Sprint Planning is typically done BEFORE a sprint begins (LOL), so how would this be "N+1" and not "N-1"? – richardlpalmer Sep 13 '19 at 18:49
• @richardlpalmer "N+1 and N" means the exact same thing as "N and N-1". Assume in the above example that N=5. Then, he's saying "planning sprint 6 before sprint 5 retro would work". – Sarov Sep 13 '19 at 18:55
• So is "N" a standard mathematical/physics/logic term? Know what it's called, so I can reference it? – richardlpalmer Sep 13 '19 at 18:58
• @richardlpalmer I'm not sure. I've been using it without thinking for so many years that if it does have a name and if I ever knew it, I sure don't remember it now. There's nothing really to the concept beyond what I've described here. – Sarov Sep 13 '19 at 19:13
• The usage of N is a kind of Metavariable. I once stumbled upon a Wikipedia article talking specifically about the usage of N, M, X, Y, Z but can't find it now. – Tiago Cardoso Sep 13 '19 at 19:58

In this context, it is borrowing from math (specifically algebra) as n is used in sequences. Sorry for some math speak, but it works like this:

t(n) = t(n-1) + 10

This would mean that the current element in the sequence equals the last element in the sequence plus 10 (if the last element was 15, this element would be 25).

Oddly, even though this is where the notation comes from, we almost never use it this way. Most commonly, n is used to denote the current element of whatever you're discussing (sprints, for example). Therefor, the current sprint is sprint n, next sprint is sprint n+1. Last sprint is sprint n-1.

In the linked question, he is referring to "Next sprint's planning happening before this sprint's retro/review". It may also be worth noting that the sprint encompassing all sprint-related events. The Planning is the very first thing that happens in the sprint and the Retrospective is the very last thing that happens.

In this context, my usage (which I may have seen in some agile training or resource, but equally well might have simply carried over from a different context) is that there are N days in the sprint, and the days in the sprint are numbered from 1 to N. This is practical because it is independent of sprint length.

So following the canonical placement in the scrum guide, Sprint Planning happens on day 1, Sprint Review and Retro both happen on day N. Other days during the sprint might be referred to as (for example) day 4 (counting forward from the beginning) or on day N-3 (counting backward from the end). One would rarely refer to N plus anything, because sprint activities are fully contained within a sprint.

Example: If I wanted our Grooming session to be 2 days before and Sprint Planning to be 1 day before the beginning of a sprint, would I call this "N-2" and "N-1", respectively?

That matches my usage.

And is the first day of the sprint "N0" or would "N0" be the grooming day?

I would never refer to N0, or N1, or N10, because N is a number to which other numbers are added or subtracted to produce a relative offset.

I would not use 0 to refer to the first day of the sprint, because IME humans naturally count from 1, not from 0. (Otherwise you would have said "the zeroth day of the sprint." ;) )