The exam formulas worth memorising cold: B.Tech, BCA and BBA

Every syllabus has more formulas in it than any exam actually needs recalled from memory. A smaller set needs to be automatic — recalled without hesitation, because a pause over the formula itself is where real time gets lost. “Know cold” means writing it correctly, unprompted, in under five seconds. If it takes longer, it belongs on a revision sheet, not on the list you trust in an exam.

1. B.Tech: the transform pairs and standard integrals.

   The Laplace transform pairs for e^at, sin at, cos at and tⁿ come up in almost every semester paper with transforms, usually inside a larger differential equation question. Standard integrals such as ∫sec x dx and ∫tan x dx, and the reduction formulas for ∫sinⁿx dx, are assumed knowledge a question builds on top of.

2. BCA: the counting formulas and the identities that connect them.

   ⁿP_r = n!⁄(n−r)! and ⁿC_r = n!⁄[r!(n−r)!] are recalled correctly by almost everyone. Fewer students know that ⁿC_r = ⁿC_n−r — that identity is often the fast route through a question that looks like it needs a much longer calculation.

3. BBA: the formulas hidden inside word problems.

   Simple interest, compound interest and the present value of an annuity rarely get asked for directly — they arrive inside a paragraph about a loan or an investment. Knowing A = P(1 + r)ⁿ matters less than being able to plug in real numbers quickly — ₹50,000 at 8% for three years — and recognise when a question needs it.

4. Test a shorter list more often, rather than reading a long one once.

   Ten formulas written from memory correctly, every day for two weeks, do more for an exam than forty read from a sheet once. Pick the formulas you keep hesitating over, not the ones you already know.

The exact formulas worth this treatment differ by paper and university, which is why we build the list from your own syllabus and past papers. Bring yours in to Sector 12 and we will work out which ten to fifteen deserve this drilling.