Yes, there is another way to format an Excel sheet to display a ratio as 1:25. Here are the steps:

1. Select the cell where you want to display the ratio.
2. Right-click on the cell and select "Format Cells" from the drop-down menu.
3. In the "Format Cells" dialog box, select the "Custom" category.
4. In the "Type" field, enter the following format code: 0":"00
5. Click "OK" to apply the format.

Now, when you enter a value in the cell, it will display as a ratio with a colon separator. For example, if you enter 25, it will display as 1:25. If you enter 50, it will display as 2:50.

Note that this format will not allow rounding, as you mentioned. If you need to round the ratio to a specific number of decimal places, you can use a formula to calculate the ratio and then round the result. For example, if you have two values in cells A1 and A2, you can use the following formula to calculate the ratio:

This formula will calculate the ratio of A1 to A2 and display it as a rounded ratio with a colon separator. You can adjust the number of decimal places by changing the second argument of the ROUND function.