There are many ways to spell monetary amounts. Pick one and use it consistently throughout your PowerPoint presentation:
- $, US$, USD, I actually like these 3-letter abbreviations, no searching on keyboards, no need to search and insert symbols, every currency has one that looks consistent
- Billion, bn
- Million, M, m
- 000, thousand, k
- Decimal point, decimal comma
- Thousand separator point, comma, or none
- Negative number with "-", or in between brackets
Unfortunately, detail does matter in presentation design...