add percentages!

README.md

@@ -194,6 +194,7 @@ Done:
 
 To (possibly) do:
 
+- [ ] Consider adding an understanding of percentages
 - [ ] With the -f command line option, the program doesn't read from stdin after finishing reading the file
 - [ ] Add functions. Now easier to do with an explicit representation of the stakc
 - [ ] Think about how to draw a histogram from samples

pretty/pretty.go

@@ -72,6 +72,8 @@ func ParseFloat(word string) (float64, error) {
 	n := len(word) - 1
 	f, err := strconv.ParseFloat(word[:n], 64)
 	switch word[n] {
+	case '%':
+		return multiplyOrPassThroughError(0.01, f, err)
 	case 'K':
 		return multiplyOrPassThroughError(1_000, f, err)
 	case 'M':