See for Mathematics there is 4 books you must study in order to have a good grasp in Mathematics for SSC CGL. The first is LUCENT SSC MATHEMATICS (Vol-1 & 2). The first part is for Arithmetic and Algebra and the volume 2 is for the advanced topics such as geometry etc. The second book is RS AGGARWAL Quantitative Aptitude book which is a very good for problem solving and important formulaes. And the third book is Kirans SSC Mathematics which is only for practice. See if you practice all this books minutely and honestly then your selection will have the maximum possibility.

To know more about SSC CGL books visit the link below:

https://competition.careers360.com/articles/how-to-prepare-for-ssc-cgl

I hope this answer helps. All the very best for your future endeavors!