<Li> Harold "Hal" Everett, Jr . (David Doremus), the oldest of the Everett kids, Hal is of above average intelligence and takes after his father's practical and skeptical persona; the two often play chess together . Hal is also a tinkerer and inventor, though his experiments often go awry; one of his inventions is a prototype of what would later become known as The Clapper . </Li> <Li> Bentley "Butch" Everett (Trent Lehman), the middle child and Hal's younger brother, who hates his real name and, when he's not eating, enjoys sports and is an occasional prankster; he unsuccessfully attempts to frighten Nanny by hiding his pet guinea pig in her bag . Butch harbors jealousy and envy of Hal and has a penchant for following in his footsteps whenever Hal takes up a new career choice, though in one episode the tables are briefly turned when, after he mimics Hal's stargazing, he happens to find a new comet and the Bureau of Astronomics decide to name the comet after him . </Li> <Li> Prudence Everett (Kim Richards), the youngest of the Everett kids and the Professor's only daughter . Prudence immediately takes a liking to Nanny when she first arrives . </Li> <Li> Mrs. Fowler (Patsy Garrett) (recurring), the Everetts' sometimes nosy neighbor . </Li>

Who played prudence on nanny and the professor