Don't let Excel's #DIV/0! error spoil your spreadsheet. If the strategy's sound, inhibit the error.
If you're the only one using the spreadsheet, you probably don't need to do a thing; you know what the error means. However, if you share the spreadsheet, you'll probably want to inhibit this error value to avoid confusion or worse — someone might think you're sloppy or even incompetent. To inhibit the display of this error, you can use the IF() function as follows:
Select cell E2 because you'll want to inhibit all of the formulas in column E, not just the one that's currently displaying an error value.
Replace the simple equation with the following function: =IF(B2=0,"",D2/B2).
Using the Fill handle, copy the new function to cells E3:E6.