Hi~ Hello~Aloha~ hahaha I'm Kim living in Seoul! Nice to meet you! 짐작해서 하십시오 means "take a guess first and then do" 짐작하십시오 means "take a guess" the biggest difference is the first sentence has 2 verbs and the other has one verb. I don't exactly know when is "~해서" used but I'll give you some examples. Ex. 생각해서 결정하십시오 means "Think first and then decide" which could be replaced with "~하고" Ex. 1. 배고파서 밥을 먹었습니다. 2. 지겨워서 게임을 했습니다. In this case, However, It is used as "cause". so.. 1. is "I was hungry so I ate some food" 2. is "I was bored so I played the game" well.. sorry for clumsy explanation.^_^;;; I hope I would help you understand it! Thank you for reading my comment! if you have any questions about my comment, please feel free to ask! Bye~! - Kim -