put two and two together
- "How did you know they were having an affair?" "I'd seen them out together a couple of times, so I just put two and two together."
值得注意的是， put two and two together and make five 这个习语指的却是“听风就是雨”，比如：
- "Why in the world did she think you were pregnant?" "I was sick a couple of times, and I guess she just put two and two together and made five."
get the wrong end of the stick
- Her friend saw us arrive at the party together and got the wrong end of the stick.