at one’s fingertips —(of facts, information, etc.) readily available thanks to thorough knowledge (also: at one’s finger-ends):
- Thanks to an excellent filing system, he has all the figures at his fingertips.
to one’s fingertips —(also: to one’s finger-ends) completely; thoroughly:
- Frank was a gentleman to his fingertips. He was always good to meet and has a word for one and all.