I felt my childrens' maths lessons at primary school were particularly woeful, insomuch as they appeared to flit between different topics. So for example a few days on long division, before moving on to a few days doing fractions, this approach may have been fine for the most capable pupils but for those who didn't grasp a concept straightaway, there didn't seem to be any time to consolidate what they had learned before moving on, they seemed to rotate everything, presumably so they didn't get bored, but personally I would have preferred them to spend ages on one thing and let it sink in. In retrospect this is how I remember my arithmetic lessons from junior school, we would be taught one thing ad nauseam. It really doesn't surprise me that employers find younger prospective employees arithmetic below par, I don't think it's their fault, but how they have been taught. In my younger son's GCSE year, I asked his maths' teacher if she could recommend a private tutor, it was at this stage I found out, that apart from the most capable, most kids were being tutored privately for this subject and his teacher confessed that she agreed with me that the approach to teaching arithmetic in junior school was unsatisfactory. Hence the number of children relying on private tuition at a later stage. I would like to point out that this wasn't a sink school and the GCSE results were and are above the national average, including those for Maths and English.
Another thing that became apparent to me when my son got his GCSE passes it included one in French, he knew less French than me, a subject I was truly abysmal at when I was at school!