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...