It depends on the Marking Scheme Published by the Board/Authority conducting the examination.
For example CENTRAL BOARD OF SECONDARY EDUCATION, Delhi have a published making Scheme for respective subjects.
The Markers are to
Consult the 'Marking Scheme' for each question, with reference to steps into which answers and awards have been divided.
If a candidate directly substitutes the values and gets the correct
answer with unit, full marks to be awarded. (say for application of Ohm's Law)
There should not be no effort at 'moderation' of the marks by the evaluating teachers. The actual total marks obtained by the student may be of no concern of the evaluators.
Half mark to be deducted if the candidate either does not write units or writes wrong units in the final answer of a numerical problem.
Students are to
Examine a question in conjunction with the Marking Scheme and find out the proximity of the answer to that suggested in the Marking Scheme.
It may therefore be instructive to obtain and go through marking scheme published by your examining body.
Hope it helps.