[put] two and two together

to evaluate the situation and all its possible outcomes in order to draw a conclusion

The origin of the idiom "put two and two together" is not definitively known, but it likely stems from the basic mathematical principle of addition, where combining the numbers 2 and 2 results in 4. It is commonly used in situations where there are clues, hints, or pieces of evidence that, when combined, reveal a larger truth or understanding.

When I saw her carrying an umbrella and wearing rain boots, I put two and two together and realized it was going to rain.
After noticing the missing wallet and the open window, I put two and two together and concluded that there had been a break-in.
When she canceled our plans and seemed distant, I put two and two together and realized something was wrong.
After hearing rumors about layoffs and seeing the company's declining profits, I put two and two together and suspected there would be job cuts.
When I saw him constantly checking his watch and looking anxious, I put two and two together and realized he was running late for an important meeting.