Are you sure you mean "letter" and not "number" ?
If number, then it is -3.
In terms of letter, well, it is a puzzle.
9 can be written as IX in Roman numerals. So, if you add S to it, it becomes SIX.
You can't add a letter. you add an integer (or a number).Adding -3 to 9 makes it 6.Another Answer:-It could be S because IX = 9 and SIX = 6
A six letter work is sicker.
You can make CLERIC
smooth
hernia
The six-letter anagram is kismet (i.e. fate, sometimes capitalized).If you added an A to these letters, you could make a mistake.
careen
dynamo
acting
Tawdry
Six letter words that can be derived from the letters begrime are: bemire. emigre. regime.
Cello is a five letter word that sounds like six letters when pronounced. The letter c is pronounced ch to make the word sound like six letters.