To answer the simple question ‘How many customers do you have?’ sounds straightforward, but it actually becomes more difficult the bigger your organisation becomes.
Duplicates and bad data hygiene play a part in making the answer less straightforward, but a more fundamental problem is the counting rules that we use to decide who the customer is.
For example in the B2C world, is your customer the household or the individual? If a student, with two addresses for term-time and holiday-time, which do you use? Do you count them twice or once?