How to understand tough questions of number system

clear your basics and practice more & more from various sites and try to acheive perfection in various type of questions and then go for higher ones do not focuss so much on number system as it is a topic of lesser importance and absolutely no value for banking exams DI and PERCENTAGE will be more benificial if you target 75- 85 % accuracy in these sections

absoutely you are right...

number system is depend on your mind an logic

how to catch them.