Is there a word that means to multiply by 1.5, or to increase by 50%?
Solution 1:
It doesn’t exist, but you could try inventing something like
sesquible
Some would quibble, but the prefix sesqui means one-and-a-half, and is used in compound names in chemistry.
Indeed, some have quibbled and suggested the more elegant:
sesquify
or
sesquate
I leave it to the classical scholars and genuine linguists to decide which is preferable.