Automtically filling non consecutive cells

[pkc23]

Hi, Total newbie with a problem I cannot solve. I want to be able to put a number in a cell and for excel to then automatically put that number into each cell next but one cell going down 10 times. So for example if I enter the number 50 in cell D10. When I click out of the cell I'd like excel to automatically put 50 into cells D12, D14, D16 etc. Only just started using simple macros and this one has me stumped.
Hope you can help. Thanks