Count Of Quarter Between Dates
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You can also calculate how many quarters there is between current day and some date (here in A2 cell).
=FLOOR(((YEAR(NOW())-YEAR(A2))*12+MONTH(NOW())-MONTH(A2))/3;1)
Results are rounded down.
You might be interested also in date duration calculator.
Template
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Further reading: Basic concepts Getting started with Excel Cell References