scheduling problem- using excel solver with binary constraint

I'm using solver in Excel to solve a linear optimization problem. I want the solution (the numbers Excel will calculate) to be binary. I set 开发者_Go百科binary as a constraint in sovler and also set as a constraint integers with greater than or equal to 1 or 0, but the program won't solve! The numbers it ends with are .99..., .83..., etc. Thoughts?

Even if you can achieve this with a spreadsheet software like Excel I don't recommend it. Spreadsheet software have poor numerical accuracy, see http://www.jstatsoft.org/v34/i04/paper .