Build a short checking habit into your process. Before you say the final number, pause for one beat and ask yourself whether the magnitude makes sense, whether the sign is right, and whether you kept track of units correctly.

A lot of ‘stupid mistakes’ happen because candidates rush the final step. Slowing down by just a few seconds can save far more time than correcting an avoidable error later.

It also helps to write intermediate steps neatly so your brain is not trying to hold everything at once. You may also find it helpful to read case interview mental math if you want a more structured way to practice this.

Units and zeroes get me all the time. Quick sanity check helps a lot.

I started narrating each step more clearly and weirdly that reduced my mistakes too.