Questions in the Numerical Ability section of AFCAT are asked from Decimal Fraction, Time and Work, Average, Ratio & Proportion and Simple Interest, Profit & Loss, Percentage, Time & Distance (Trains/Boats & Streams). To prepare for this section, the candidates are suggested to read the AFCAT books mentioned below: Quantitative Aptitude for Competitive Examinations- RS Aggarwal/ S Chand Publishing; Objective Arithmetic- S Chand ,Quantitative Aptitude & Data Interpretation- Disha Publication