If you want to clear the IBPS RRB PO, RRB OA & NIACL Assistant exam, then do the best of these topics .

                                           
1. Reasoning 

Seating Arrangements & Puzzle 
Set-1
Set-2
Set-3
Set-4
Set-5
Set -6
Set-7
Set-8
Set-9
Set-10
Set-11
Set-12
Set-13
Set-14
Set-15
Set-16
Set-17
Set-18
Square seating arrangement
Linear Arrangement
Set-1
Date and Month memory based puzzles
Memory-based puzzles asked in SBI PO Prelims 2018 exam
SBI Clerk Prelims Memory Based puzzles and Seating arrangement 23-24/06/2018
Inequality
Syllogism
Coding-Decoding

2. Quantitative Aptitude 

Basic Calculation Tips and Trick for fast trick
Simplification
Approximation
Missing Number  Series
Set-1
Set-2
Set-3
Set-4
Set-5
Set-6
Set-7
Quadratic Equation
Word Problem
Set-1
Set-2
Set-3
Set-4
Set-5
Set-6
Set-7
Set-8
Set-9
Percentage
Profit and Loss
Mixture and Alligation
Time and Work
"Time and Work", "Pipe and Cisterns"
Mensuration
SI & CI
Time, Speed and Distance 
Boat and Stream
D.I.
Probability
IBPS RRB PO Prelims Previous Year Paper 2017: Memory-Based Paper PDF

Banking Awareness 
Most important abbreviation