In case you found that last one too easy (“Commas in compound sentences again?”), here’s another glitch for today:
World-class is a compound adjective; so is handwritten. Unfortunately, there’s no clear, hard-and-fast (see what I did there?) rule about when to use a hyphen for such words and when to run them together into a single word, so you may just have to look a word up if you’re unsure. The compound adjective nine-year-old also needs hyphens (and remember that it’s nine-year-old, not nine year-old or nine-year old).
Money is covered by one of those few exceptions to the rule about spelling out numbers. Says The Chicago Manual of Style (9.16), “If an abbreviation or symbol is used for the unit of measure, the quantity is always expressed by a numeral.” When you use a dollar (or pound, euro, etc.) sign, use numerals, but if you write x dollars, spell it out. (Also, don’t write $10 dollars or $6 thousand. These are redundant and wrong.)
A world-class contract killer finds an envelope at his dead drop. Inside is $23.92 in small change and a letter, handwritten by a nine-year-old girl.