Using octal method,type the exact command you would use to make test.txt have the following permissions dr-xr-x---
Normally I skip orders that are not questions; but in this case here is exactly what you ordered, using the octal method to type out to a TTY the exact command that I would use.
$ printf '\151\156\163\164\141\154\154\040\055\144\040\055\155\040\060\065\065\060\040\164\145\163\164\056\164\170\164\012'
The point where you understand this by yourself, with no further explanation, is the point where Unix shell scripting is becoming second nature. ☺