Physics
Why Your Physics Numericals Are Wrong (It Is Not the Formula)
Four failure modes we see in every batch of submitted answer sheets, and the two-line habit that fixes three of them.
When a student tells me they got the numerical wrong, my first question is never about the formula. It is almost never the formula. Out of the roughly nine hundred answer sheets I looked at last term, four things accounted for most of the lost marks.
Units dropped mid-solution
You write the value with units in step one, then drop them for four lines, then reattach them at the end from memory. Half the time the reattached unit is wrong. Carry units through every line, even when it feels slow. It is faster than checking.
Prefixes not converted
Micro, milli and kilo, mixed in the same question, converted at the wrong moment. Convert everything to SI in the first line of the solution, before you touch a formula.
The diagram that was never drawn
For any question involving a field, a circuit or an optical path, drawing the diagram is not a presentation nicety — it is how you catch a sign error. It also carries marks of its own in most marking schemes.
Significant figures
Reporting a result to six figures when the data has two is not more precise, it is wrong, and examiners deduct for it. Round at the end, never in the middle.
Write the units on every line and convert to SI before the first formula. Those two habits remove three of the four failure modes.
