Golomb's Gambits: Letter Interchanges

The following puzzle first appeared in the April 2001 issue.

The problems in this column involve situations where one letter is replaced by another. You may include examples even when there is another spelling where the letter substitution does not occur.

The letters F and V often interchange in closely related English words. How many cases of each of the following can you find?

a. A noun ending in –F (or –FE) becomes a plural ending in –VES. (Example: wolf—wolves. I found 15 more.)

b. A noun ending in –F (or –FE) changes to a closely related verb ending in –VE. (Example: grief—grieve. I found 10 more. There is some overlap with answers to question 1.a.)

c. Cardinal numbers ending in –VE become ordinal numbers ending in –FTH. (Two basic examples, not counting compounds.)

Illustration of Solomon Golomb reads 'Scroll down for solution'

Golomb's answers:

a. calf/calves elf/elves half/halves hoof/hooves knife/knives leaf/leaves life/lives loaf/loaves scarf/scarves self/selves sheaf/sheaves shelf/shelves thief/thieves wharf/wharves wife/wives wolf/wolves

Note also: ourself/ourselves, yourself/yourselves

b. belief/believe calf/calve grief/grieve half/halve life/live proof/prove safe/save serf/serve shelf/shelve strife/strive wife/wive

c. five/fifth twelve/twelfth (The compounds are of the form sixty-five/sixty-fifth.)