There is a thread on the my.unisa discussion forum, which discusses difficulty experienced when trying to do the Big-O exercises.

I agree, and I would like to see some worked examples, specifically covering O(log(n)) and O(n log(n)).

Also the assignment questions give a base running time of 10 s for input size 100, does this mean that we need to work out the input number for 1 s and then apply that to calculate the running time for input size 1000.

Finally the reverse calculation where we are given 80 s running time and need to calculate the input size for a function with cubic growth, is a bit tricky.

Luckily this is multiple choice because I can kind of work it out and then choose the option which most closely matches by calculations, however this approach to math is frustrating. I would really like to see some more worked examples, and an explanation of the method of calculation.