cheapest
Cheapest
Hottest.
The comparative form of the word "cheap" is "cheaper." The superlative form is "cheapest."
cheapest
cheper
cheaper, cheapest
cheaper, cheapest
cheaper, cheapest
the most famous
Itchier is the comparative form and itchiest is the superlative form.Comparative: My new shoes are itchier than my old shoes.Superlative: Those cheap shoes you can get at the local department stores are the itchiest shoes I've ever tried.
Sleep is a noun and does not have a superlative. Sleepy is an adjective and the superlative is "sleepiest."
The superlative for willing would be "most willing." There is no one-word superlative.
"Studying" is not a superlative, as it is not an adjective. "Most studious" is a superlative of "studious."