Estimation Techniques — Prelims Strategy

Prelims Strategy

For CSAT Prelims, develop a systematic estimation hierarchy: (1) Always estimate first to establish answer range before attempting exact calculation, (2) Memorize key approximations - 25%=1/4, 33%=1/3, 50%=1/2, 67%=2/3, and common decimal equivalents, (3) Practice the 30-second rule - if estimation clearly points to one option, move on; if not, invest additional time in exact calculation, (4) Use answer choice spacing as your guide - wide spacing (>15% difference) favors estimation, close spacing (<10% difference) may require precision.

Master the elimination strategy: use order of magnitude estimation to eliminate obviously wrong options first, then apply percentage approximation to narrow down to the correct choice. For data interpretation questions, develop visual estimation skills - practice reading charts and graphs to within 5-10% accuracy without detailed calculation.

Common traps to avoid: over-rounding (making approximations too crude), compound error accumulation (small errors adding up), and estimation bias (consistently rounding up or down). Time allocation strategy: spend maximum 60 seconds per estimation-suitable question, reserving longer time for questions requiring exact calculation or complex logical reasoning.