(כג ו) “להם אמור ישראל בני את תברכו כה לאמר בניו ואל אהרן אל דבר”
Harav Menachem Mendel Lazar, the Rav of Stryzow, explained:
The word כה is comprised of two letters: כ which is numerically equivalent to 20, and ה– which is equal to five. We can explain from this an allusion to the mitzvah of reciting one hundred brachos a day: תברכו ה“ כ– you should recite 20 times 5 brachos a day – equaling one hundred brachos.