The RRB Group D examination will most likely be held in July 2022 by the Railway Recruitment Board (RRB). If you are willing to work for the Indian Railways, you should read this article at least once. I'm pointing you in the right direction for getting good grades and securing your seat.

Mathematics:
Begin with simple topics that require the use of formulas or simple calculations, and then progress to more difficult topics.
Reasoning:
Set aside some time each day to practise questions from the easiest topics that require common sense, and brush up on the underlying theory as well as the steps to solving them for more difficult topics.
General Science:
Go over all of the concepts covered in the NCERT Science textbooks for Classes 9 and 10.
General Knowledge and Current Events:
For Current Affairs, concentrate on national and international events from the previous six months. Make an effort to read and memorise information on the most important General topics.
Test Yourself:
After you've finished each topic, take as many Sectional Mock Tests as you can. Try the full-length RRB Group D Mock Test to put your knowledge to the test. To test your knowledge, take the Free RRB Group D Mock Test at Testwale.com.

https://www.testwale.com/test-series/14/rrb-group-d/