I never counted how many diapers I changed with any of my kids, but I remember when my kids were at the newborn stage, I was changing their pants upwards of a dozen (or more) times a day, and having used cloth diapers, my guess is, I went through more diapers than a mother using Pampers would have gone through.
Nonetheless... 12 diapers per day @ 7 days a week = 84 diapers per week
In a month... 336 diapers
In a year... 4000 (plus) diapers
For a 2-3 period... 8000-10,000 diapers.
Adding, I double diapered always, so that would have bumped-up the number of diapers I went through in my home.
6 kids @ 8000-10,000 diapers per child... approx. 60,000 diapers.
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Putting things into perspective for the family in question... approx. 150,000 diapers.
Can't imagine what the bill would be for that if disposables were/are used.