When working with time values in Excel, it's important to make sure that the values you're using are actually valid time values. There are a few ways to do this, but the easiest way is to use the ISNUMBER and ISTEXT functions together. The ISNUMBER function will return TRUE if the value is a number, and the ISTEXT function will return TRUE if the value is text. So, by using these two functions together, you can check to see if a value is a valid time value or not.
To use these functions, simply enter the following formula into a cell:=ISNUMBER(value)&ISTEXT(value)
Replace "value" with the cell reference that contains the value you want to check. If the result is TRUE, then the value is a valid time value. If the result is FALSE, then the value is not a valid time value.
It's also worth noting that you can use the TIMEVALUE function to convert a text string into a time value. So, if you have a cell that contains a text string that looks like a time value (for example, "1:30 PM"), you can use the TIMEVALUE function to convert it into an actual time value. To do this, simply enter the following formula into a cell:=TIMEVALUE(text string)
Replace "text string" with the cell reference that contains the text string you want to convert. The result will be a time value that you can use in calculations.