Keep Formula Cell Reference Constant In Excel or Create absolute Cell References
To keep cell reference constant in formula, you just need to add the $ symbol to the cell reference.
When you use relative cell reference in a formula, it will automatically adjust when you use the Fill Handle to apply it to a different location or copy and paste it to another cells. . In many cases, you would like the cell reference staying constant rather than adjusting automatically.
Summary of absolute cell reference uses:
Allows the row reference to change, but not the column reference.
Allows the column reference to change, but not the row reference.
Allows neither the column nor the row reference to change.