calculating
Carefully planning actions to get what you want selfishly.
To be calculating means to carefully plan your actions to get what you want, often in a cold or manipulative way. A calculating person thinks several steps ahead, like a chess player who plans their next five moves while you're still thinking about your first one. The word usually suggests selfishness: someone who's calculating might pretend to be your friend only because they want something from you, or they might say just the right things to get out of trouble even though they don't mean it.
The word comes from making calculations (doing math), but calculating people aren't doing arithmetic. They're doing something more like social math, figuring out exactly what to say or do to achieve their goal. A calculating student might compliment the teacher right before asking for an extension, not because they genuinely appreciate the teacher, but because they've figured out that this strategy works.
Not all planning makes someone calculating. Thinking ahead about how to ace your science project shows good judgment. But if you're only nice to your lab partner because you want them to do all the work while you take credit, that's being calculating. The word captures that uncomfortable feeling when you realize someone's kindness was really just a strategy.