-s + 20 is one way but it is not clear what purpose is served by writing it in that way.
The 1920s came before the Great Depression.
Two other ways to write 5.9 over 100 are: 59 over 1000 and 0.059
2 2
Ways to write one billion is: one billion,1 billion,1,000,000,000,you can write it in roman numeral several different ways,with tally marks, etc.
42993.8m 4299380cm
406/100 406%
37%; 0.37
0.79 or 79/100
12% or 12/100
You can write it as 103. That would be the most common way, but there's many other correct ways to write it.
4/10 or 0.39999 recurring.
1/5 and 2/10