Calculate Day Number by Data Range

[Datatellsall2]

Hello -

I'm looking to calculate (via a function) the exact day number for a given time range based on a unique identifier. Please see my example below:

Unique Identifer	Date of Entry	Day Count (Based on Date Range of Unique Identifier) Trying to create function for this column
100	1/2/18	1
100	1/5/18	4
100	1/20/18	19
101	2/9/18	1
101	2/12	4

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Thanks in advance,
M

 

[sheetspread]

This?

Excel 2010
	A	B	C
1	Unique Identifer	Date of Entry	Day Count (Based on Date Range of Unique Identifier)
2	100	1/2/2018	1
3	100	1/5/2018	4
4	100	1/20/2018	19
5	101	2/9/2018	1
6	101	2/12/2018	4
Sheet4

Cell Formulas
Range	Formula
C2	=B2-VLOOKUP(A2,$A$2:$B$6,2,0)+1

 

[Datatellsall2]

Perfect! Thank you!

M