Student or Learner
"I suppose so" where it is used and what does it mean?
Merriam-Webster's Learner's Dictionary
◊In responding to a question, the phrase I suppose (so) is used as a way of agreeing or saying “yes” when you are not certain or not very excited or interested.
▪ “The pink one is prettier, isn't it?” “I suppose.”
▪ “Do you want to come along?” “I suppose so.”
◊The phrase I suppose not is used as an informal way of agreeing with a negative statement or of saying “no.”
▪ “That wasn't a very smart thing to do, was it?” “I suppose not.”