MROUND rounds to nearest values based on a supplied multiple. When you supply "0:15" as the multiple, Excel internal converts 0:15 into 0.0104166666666667, which is the decimal value that represents 15 minutes, and rounds using that value.
You can also express 15 minutes in a formula with this formula:
The formula above divides 15 by 1440, which is the number of minutes in one day. So, to Excel, these formulas are identical:
The Excel FLOOR function rounds a given number down to the nearest specified multiple. FLOOR works like the MROUND function, but FLOOR always rounds down.
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