The standard practice in testing potential floor traders was to require that they could quickly calculate positions and potential risks for futures and option products.
Today much of this is auttomated but you still need to be a couple of steps ahead of the market, calculating potential positions and risks - to some degree - in your head.
You probably wont get past this requirement if you are attempting to get a job: you will just need to practice these skills which can be developed through repetition .....
. I was said that at 2 years old my father had learned me multiplication up to 16 (so that I was exposed in family shows) - whereas as adult I merely know it up to ten so I made a mental regression 
. I was considered as very gifted when young and as I was only 5 I was put in a class with much elders than me with 10 years old children and the teacher the first day asked me to go to the board and made a division of 3 numbers by 2 numbers. I knew how to make a division by one number but not by two numbers so I couldn't answer and this #@!' teacher punished me by ordering to stand up on my knees on the table for the rest of the morning and before that he hit my fingers with a hard stick : I cried because I found that it was really an injustice to ask me that as I was so young and since that time I think I hate calculation