2.13 Quick Reference Formula Sheet

Before moving to shortcuts, consolidate every formula from this chapter into one revision block — this is what you should be able to reproduce from memory in the last 10 minutes before the exam:

• SI = PRT/100; A = P + SI = P(1 + RT/100)
• CI (annual) = P[(1+R/100)^T − 1]; A = P(1+R/100)^T
• Half-yearly: rate → R/2, time → 2T. Quarterly: rate → R/4, time → 4T.
• CI for fractional years = whole-year CI, then SI on that amount for the fractional part
• CI − SI (2 years) = PR²/10000
• CI − SI (3 years) = PR²(300+R)/10⁶
• SI doubling time: T = 100/R. Tripling time: T = 200/R.
• SI installments: P(1+nR/100) = x[n + n(n−1)R/200]
• CI installments: P = Σ x/(1+R/100)^t for t = 1 to n
• Population growth: A = P(1+R/100)^T. Depreciation: A = P(1−R/100)^T
• Effective annual rate = [(1+R/100n)^n − 1] × 100

Keeping this single sheet fresh in your mind eliminates almost all formula-recall delay during the exam, leaving your time budget entirely for arithmetic and option-elimination.