Eighteen is the numerical value of the Hebrew word "chai" which means "life." It is a Jewish custom to give monetary gifts in increments of 18, thus symbolically blessing the recipient of the gift with a good long life.
When giving charity, the number 18 has another significance. It expresses our prayer that the merit of the charity given stand in our good stead, that we be blessed with life and prosperity.
Chani Benjaminson
Chabad.org

I have heard that it is now “a thing” to give $101. I can only think that the Gamatria is קא, which many for use instead of Hashem’s name in songs, like Ka Ribbon, or the idea of studying 101 times is better than average, but this doesn’t seem to be the answer. Any ideas?