Pause macro to enter value, continue macro

Hi guys,

I am creating a macro at the moment that requires two values to be entered before it can complete its calculations. I've been thinking of how to do this while minimising the amount of actions people have to take (not so much to save effort as to stop people from breaking things).

Ideally I would like a message box to pop up and asking for a value (say, 'how many days'), and when the amount of days has been entered and the user has clicked OK that value being recorded in cell B1 on sheet4, and the macro happily carrying on. But I don't know if that is possible.

I was thinking of simply ending one macro on the correct cell, and in big black letters in front of it putting 'how many days' in cell A1, followed by a button saying 'continue', and linking that button to a second macro. But I get the sheet from an external source and run the macro from my personal file, and don't know how to write a macro to add a macro button.

So now I am wondering if it is possible to pause the macro until a value has been entered into cell B1 on sheet4, and then carrying on with the macro? At the moment I am simply stopping on the correct cell with one macro, and running the second afterwards.

Does anybody have any suggestions?

Cheers.

Fantabulous. Thank you most kindly.