Help with Excel a moving Link

Hi,

Need some help please, how do I link a Main Summary worksheet to another if I always want to link the last cell that has been typed in the other sheets....so for example I have 15 different sheets and on my main sheet I would like to put in a link that will always link to the last figure entered on the spreadsheet, so technically its a moving link,

so if I have for example on line 1 on sheet 2 a figure of 100 the main sheet will pick up 100 for that summary sheet, if I go and add a line to my sheet 2 and say enter 200 in the next box moving down, I would like the main sheet to pick up the last cell I entered automatically and put 200 on my main sheet, is there a way please? Ie so I am trying to link to a cell that is always the last typed on the spreadsheet, but obviously when I add to it it moves....Thankyou