AEEE common mistakes
AEEE · Understand the traps and how to avoid them.
In Mathematics, applying a formula (for example the sum of an infinite geometric series) without first checking convergence or domain conditions, then reporting the divergent-case answer.
Under timed conditions candidates pattern-match the question stem to the most familiar formula and skip the one-line validity check, because the check feels like wasted time when the answer 'looks' standard.
What to do instead
Before substituting, write the formula's precondition beside it (|r|<1, denominator ≠ 0, x>0 for logs). Spend ten seconds verifying each condition against the given data; if it fails, the problem is a trap and needs a different route.
In Physics, computing a numerical answer in mixed units (grams with metres, cm with m/s²) and writing it without converting to SI.
Exam stems often quote data in convenient units (g, cm, μC, minutes) while the standard formula assumes SI. Candidates substitute the numbers as printed and the arithmetic is clean, so nothing signals an error.
What to do instead
Convert every given quantity to SI in a dedicated first line before touching the formula, and carry units through the calculation so a mismatch shows up dimensionally. Train by always writing units at each step, not only in the final answer.
In Chemistry, balancing an equation by adjusting the subscripts of a product to make atom counts match instead of placing coefficients in front of the species.
It is the quickest way to make the counts 'work', and candidates under pressure prioritise a balanced-looking line over chemical validity, forgetting that changing a subscript changes the compound's identity.
What to do instead
Adopt a strict rule: only coefficients may be written to the left of a formula; subscripts are untouchable. Balance by inspection starting with the most complex species, then verify each element's count on both sides as a separate check.
In Quantitative Aptitude, treating percentage change as symmetric - computing a 20% increase then a 20% decrease and concluding the value returns to the original.
The arithmetic 1.2 × 0.8 = 0.96 is easy to fumble mentally, and the intuition 'up then down by the same amount cancels' feels obviously true, so no calculation is attempted.
What to do instead
Convert every successive percentage change into a multiplier and multiply them. Memorise the standard result that a rise of p% followed by a fall of p% leaves a net loss of p²/100 percent, and check the sign and magnitude against that benchmark.
In English, choosing an answer because the option 'sounds right' in a grammar or vocabulary item without identifying the specific rule or word sense involved.
Candidates rely on spoken-language intuition, which is unreliable for formal written grammar (subject-verb agreement with collective nouns, correct preposition collocations) and for near-synonyms that differ in register.
What to do instead
For each option, state the rule that would make it correct or wrong (tense sequence, preposition collocation, countability). If you cannot name a rule, flag the item and return to it rather than committing on feel.
In Mathematics, losing solutions in trigonometric or algebraic equations by dividing both sides by an expression that can be zero (for example dividing by sin x or by x).
Dividing simplifies the equation to a familiar form and feels like progress; the lost cases are invisible once the factor is gone, so the error never surfaces during checking.
What to do instead
Never divide by a variable expression. Factor instead, set each factor to zero, and solve each branch separately. Explicitly list the case 'expression = 0' as one of the solutions before simplifying.
In Physics, treating a scalar quantity as a vector (or vice versa) - adding speeds arithmetically in a two-dimensional relative-motion problem, or ignoring the direction of a force when resolving components.
Many textbook drills are one-dimensional, so candidates default to adding magnitudes. Diagrams are often skipped under time pressure, hiding the angle between the vectors.
What to do instead
Draw a quick vector sketch before computing, choose axes, and resolve into components. If two velocities are not collinear, use the cosine rule or components rather than direct addition, and sanity-check the resultant lies between the difference and the sum of magnitudes.
In Chemistry, confusing the mole concept with mass - comparing equal masses of two substances and assuming equal numbers of particles, or using molar mass in place of Avogadro's number.
Mass is the tangible quantity in the question stem, and the conversion step (n = m/M) is treated as a formality rather than the core of the problem, so equal-mass-equals-equal-moles slips through.
What to do instead
Start every stoichiometry problem by converting all given quantities to moles in an explicit line, then work in moles throughout, and convert back to mass or volume only at the end. Check the direction of each conversion with a rough order-of-magnitude estimate.
In Quantitative Aptitude, solving time-and-work or speed-distance problems with a single equation when the problem involves two rates acting simultaneously, producing an answer that matches one rate rather than the combined one.
The combined rate is an abstraction; candidates latch onto the more concrete individual rate and stop when the arithmetic yields a 'nice' number, which these problems are designed to produce.
What to do instead
Write the rate of each agent per unit time, add rates for simultaneous work (or subtract for opposing motion), and only then invert to get time. Verify by asking whether the combined time is less than the fastest individual time - if not, the setup is wrong.
In English, misreading a reading-comprehension question as 'what is true' when it asks 'what can be inferred' or 'the author's tone', and selecting an option that is stated in the passage but does not answer the question asked.
The true-but-irrelevant option is deliberately familiar text from the passage, and recognition of the wording substitutes for checking what the question actually demands.
What to do instead
Underline the question's operative word (infer, tone, purpose, EXCEPT) before reading the options. Reject any option that merely restates the passage when inference is required, and require textual evidence for the chosen option before moving on.