A while ago, I was watching a video about teaching children to count when these challenges suddenly occurred to me. Note that they may be easy in other languages (eg. in German you have: eins, zwei, drei which will solve the last one) so I’m limiting the answers to English only.
Think of a number beginning with “t”.
Think of a number beginning with “o”.
Think of a number beginning with “p”.
Think of a number beginning with “m”.
Think of a number beginning with “z”.
Edit: Also, all numbers are less than a billion.