Need help from excel formula

Hello,


I want a formula in excel : in a worksheet ina single cell an amount will display which
will be written in another worksheet . Example : in sheet A cell no. B1,B2,B3 and so on amnt. is wtitten and in sheet B cell no.D4 the amnt. will display. when I put a figure in B1 in sheet B the figure will display in sheetB D4 & again when I put a figure in B2 again the figure will display on Sheet B cell D4 and so on . It means in cell no.D4 all the amnt. will over write & display which will be written on sheet A cell D4.