Validate cell to accept current time

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To enable a person to enter current time in a cell, enter the following formula in Data > Validation > Custom

=ABS(A1-(NOW()-INT(NOW())))<(1/(60*24))

In this validated cell now, a person can enter time either by pressing Ctrl+Shift+; or by simply typing in the time entry.  The validation rule is such that it will accept only time which is within a minute of current time.  Change the 1 in the formula to change the 1 minute logic.

Sum highest n numbers based on conditions

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Assume a two column database with names in column A and numbers in column B.  Names in column A may be repeated.  If a user types a certain name in a cell, a formula should sum the highest three values from column B for that name.

Depending upon the version of MS Excel which you are using, there could be two ways to solve this problem

Solution for MS Excel 2010 and higher versions

If you are using the PowerPivot add-in, then a simple DAX formula can solve this problem.

Solution for all versions of MS Excel

While this solution works for all versions of MS Excel, it uses an array formula (Ctrl+Shift+Enter).  Array formulas, if used extensively in the workbook, adversely effect the system's performance.

You may refer to my solution in this workbook.

Return closest numeric match

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In range A2:A6, the numbers are 7.5, 2, -12, 11.2 and 8.  In cell B8, a user enters 8.  One may want to answer the following questions:

1. Return the closest number which is less than or equal to the number in cell B8
2. Return the closest number which is greater than or equal to the number in cell B8
3. Return the closest match

You may refer to my solution in this workbook.

Count unique values with conditions

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There is a three column database with month in column A, numbers in column B and names in column C.  I want to count unique numbers in column B for a specific month and name provided by the end user.

Depending upon the version of MS Excel which you are using, there could be two ways to solve this problem

Solution for MS Excel 2010 and higher versions

If you are using the PowerPivot add-in, then a simple DAX formula can solve this problem.

Solution for all versions of MS Excel

While this solution works for all versions of MS Excel, it uses an array formula (Ctrl+Shift+Enter).  Array formulas, if used extensively in the workbook, adversely effect the system's performance.

You may refer to both solutions in this workbook.

To count unique values with conditions on large databases, you may refer to the following link

LOOKUP where search string appears multiple times

{243 Comments}

In a list with multiple occurrences, the VLOOKUP() function in Excel will only return the first occurrence of the string being searched.

Depending upon the version of MS Excel which you are using, there could be two ways to solve this problem

Solution for MS Excel 2010 and higher versions

If you are using the Power Query add-in, then a few simple steps (no formulas at all) can solve this problem.  The result will be dynamic and refreshable (just as in a Pivot Table)

You may watch a short video of my solution here

Solution for all versions of MS Excel

While this solution works for all versions of MS Excel, it uses an array formula (Ctrl+Shift+Enter).  Array formulas, if used extensively in the workbook, adversely effect the system's performance.

I  have presented three cases in the this workbook.

You may refer to my explanation of the array formula here.