You could try this formula:

```
=SUM(IFERROR(LEFT(A1:J10,LEN(A1:J10)-1),0)*1)
```

Adjust the range as necessary.

This will blanket a whole range, remove the last character of each, then add them together.

If you really have only `L`

or `R`

but can have bare numbers like `10`

, then you could use this instead:

```
=SUM(IFERROR(SUBSTITUTE(SUBSTITUTE(A1:J10,"R",""),"L","")*1,0))
```

**NOTE: Both of the above formulae should be called with **`Ctrl`+`Shift`+`Enter` after having input them in a cell since they are array formulae.

EDIT: To get alternate columns, you can use this:

```
=SUM(IFERROR(SUBSTITUTE(SUBSTITUTE($C4:$R4,"R",""),"L","")*{1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0},0))
```

Again, you need to use `Ctrl`+`Shift`+`Enter` for it to work properly.

For the next column (the ones that should be installed), you simply change the order of the 1's and 0's:

```
=SUM(IFERROR(SUBSTITUTE(SUBSTITUTE($C4:$R4,"R",""),"L","")*{0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1},0))
```

Notice that there is a number for each of the cells within the range (C4:R4 has 16 cells, therefore there are 8 1's and 8 0's)

`100BT`

) – Jerry Jan 28 '14 at 9:35