Excel formulas don't put values in cells, they read values from cells and return the calculated result.
To put values in cells, you need VBA.
Per the example in post #4, you have 1 in A1.
What do you want to happen when the user puts a 7 in B1?
Do you want the user to have to press a button or some other action to cause the result you want.
What do you want to happen when the user changes the 1 in A1 to 5?