To be clear, 255 is a limit on the AppleScript side; Excel allows up to 8192 characters in a formula.

Try this script:

```
tell application "Microsoft Excel" -- version must be > 2019
tell active sheet
-- fml is 255 characters
set fml to "=LET(
char1,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
char2,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
char3,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
char4,MID(\"ABCDEFGHIJKLMNOPQ\",RANDBETWEEN(1,16),1),
CONCATENATE(char1,char2,char3,char4)
)"
set formula2 of range "D13" to fml
set chars to evaluate name fml
end tell
end tell
```

and everything works. The formula result will be output to cell D13 and the `chars`

variable will be set to the result of evaluating the formula.

But try this script:

```
tell application "Microsoft Excel" -- version must be > 2019
tell active sheet
-- fml is 256 characters
set fml to "=LET(
char1,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
char2,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
char3,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
char4,MID(\"ABCDEFGHIJKLMNOPQR\",RANDBETWEEN(1,17),1),
CONCATENATE(char1,char2,char3,char4)
)"
set formula2 of range "D13" to fml
set chars to evaluate name fml
end tell
end tell
```

and nothing will be output to Excel and the value of `chars`

will be `missing value`

.

(Note: I specify version must be > 2019 just because using a `LET`

function was the easiest way for me to construct a long formula and `LET`

is only available in post-2019 versions of Excel.)

*But*, you can absolutely paste the second formula into the formula bar of Excel and it will work.