Aptitude and Computer Knowledge
What the exam tests
Aptitude tests numerical and logical reasoning; computer knowledge tests basic hardware, software, internet, e-courts and cybersecurity.
Core rules
- Percentages: successive changes are not additive; use multiplying factors.
- Time and work: combine rates; reciprocal of days gives one day's work.
- Coding-decoding and series: look for letter positions, reversals and arithmetic patterns.
- Computer: CPU is the processing unit; RAM is volatile; ROM is non-volatile; a digital signature uses asymmetric cryptography.
- E-courts: e-filing, virtual hearings, and the National Judicial Data Grid are common topics.
Worked example
A shopkeeper marks an article 25% above cost and gives a 10% discount. Let cost be ₹100. Marked price is ₹125. Selling price is 90% of ₹125 = ₹112.50. Profit is ₹12.50, i.e., 12.5%. Do not add 25% and subtract 10% to get 15%; successive percentage changes use factors 1.25 × 0.90 = 1.125.
Traps
A 25% increase and a 20% decrease do not cancel. In time and work, do not average days; add rates. In computer questions, do not confuse RAM with ROM or a digital signature with a scanned signature.