Where Marks Actually Go
Look at a marked paper and the pattern is rarely broken arithmetic. It is the right method applied to a slightly different question: the area when the perimeter was asked for, the discount instead of the final price, the answer in metres when the question said centimetres.
Those are reading errors, and they are cheaper to fix than any amount of extra practice.
Find the Actual Verb
Underline what the question tells you to produce. Calculate, estimate, explain, compare and prove all demand different things, and an explanation written where a proof was requested will not score full marks however true it is.
Check the Units Before You Start
If lengths arrive in centimetres and the answer must be in square metres, decide when you are converting before you calculate, not after. Converting halfway through a chain of working is where factors of a hundred go missing.
Note the Required Form
"Give your answer to three significant figures", "leave it in terms of pi", "as a fraction in simplest form". Each of those is a mark. Circle the instruction while you read it so the finished answer gets the right treatment.
Ask What Would Be Reasonable
A person is not 4 metres tall and a bus fare is not 900 pounds. Holding a rough sense of a plausible answer before starting means an implausible result gets questioned rather than written down.
Re-read Before You Move On
Ten seconds checking that the answer matches what was asked catches the majority of these errors. It is the highest-return habit available in an exam, and it costs nothing but discipline.
