Earn the trace, logic and binary marks in OCR A-level Computer Science.

H446 lessons you can step through, questions that name every slip, and a free trace table trainer.

Try an exam-style trace

Structured question 110 marks

The program below builds a sequence of numbers.

a = 1b = 1for n = 1 to 4    c = a + b    a = b    b = cnext nprint(b)

(a) Complete4 marks

the trace table: one row for the end of each pass, then one row for the print.

(b) State1 mark

the value printed if the loop runs for n = 1 to 6.

why the order of lines 5 and 6 matters.

0 words

(d) Write3 marks

a loop that prints every even number from 2 to 20.

Step through the code and watch every variable change, then fill the trace table yourself.

Each wrong option names the mistake that makes it tempting.

She quotes the sentence that earns each mark and flags the claim that loses one.

Every lesson and question opens with a free account. The full course and its price come later.