You can vibrate a rune, either for the number of times associated with its number or a multiple of that number, for example the rune of healing and banishing depression, Wunjo, is the 8th rune in the alphabet with the associated number 8. You can vibrate this rune either for 8 times or a multiple of 8 (16, 24, 64 etc.)
Alternatively, there are powerful numbers that can be used irrespective of rune. Some of these numbers are 36, 40 and 100.