Switching from Windows to Mac is already a lesson in patience, but when your spreadsheet formulas start failing for no visible reason, that patience gets tested fast. The user who posted this question is doing everything right: following along in ICT lessons, applying the syntax they were taught, and troubleshooting on their own before asking for help. The problem is not their understanding of formulas. It is a quiet, frustrating difference in how Mac and Windows handle regional settings, and it trips up more people than it should.
The semicolon versus comma issue comes down to locale, not logic. On Windows, many regional formats default to a comma as the argument separator in spreadsheet formulas. On Mac, especially with certain system language settings, the semicolon is the expected separator. So when this user types `=ROUNDUP(A2*$M$1/B2;2)` and gets an error, it is not because the formula is wrong. It is because the Mac's spreadsheet application is reading that semicolon as a literal character instead of a structural part of the formula. Changing number formatting does nothing because the issue is not how numbers display, it is how the formula parser interprets punctuation.
The practical fix is straightforward: either switch the system's region setting to match the format your lessons use, or adjust the formula to use the separator your Mac expects. In most cases, changing the region to a country that uses commas as decimal separators and semicolons as argument separators will align the Mac with the Windows syntax. Alternatively, simply replacing semicolons with commas in the formula will work if the Mac is set to a region where commas separate arguments. Neither option is difficult, but the first attempt to fix it by poking at number formatting is a dead end, and that is exactly the kind of misleading clue that wastes time.
This is a small problem, but it reveals something larger about moving between platforms. The tools we use are not neutral; they carry assumptions about how we work, and those assumptions shift depending on where you are. The user is not doing anything wrong. They are adapting, and adaptation takes trial and error. The real lesson here is not about semicolons. It is about learning to ask the right question when a formula fails, and recognizing that the answer often lives in settings you would not think to check. If you are stuck on a Mac after years of Windows, start with the region settings. That is where the answer is hiding.