An alternative to Ian's suggestion: Use Copy&Paste.
Enter cs600 in the first cell and confirm the entry by pressing return or tab.
Click on the cell to select it.
Drag to select the rest of the cells. Ignore the incremented values that are filled as you do this.*
*If you are filling many cells, you may also select the range by clicking on the first cell, then shift-clicking on the last cell in the range.