it's "red hammer" because you mentally want to kill a person who's making you do the calculations, red is the colour of blood and hammer is a good tool for killing (i thought of axe, though).
well, the other explanation: associations with former USSR - red flag and a hammer, well, there's a sickle too, but who has "sickle" for first association with USSR?
green screwdriver, im noticing that more than two percent of the RHP population isnt following the supposed outcome, could we have found a glitch in the puzzle?!?!?
My first thought is that a majority of people will say red hammer if I just asked them to name a color and a tool. Maybe the arithmetic is just a distraction.