Speech -- Write With (AP) Style ...

Is it October 31 or October 31st or Oct. 31?

In this instance, it's the latter. In AP Style under dates . . .

Always use Arabic figures, without st, nd, rd or th. See months for examples . . .

Also, under months . . .

Capitalize the names of months in all uses. When a month is used with a specific date, abbreviate only Jan., Feb., Aug., Sept., Oct., Nov. and Dec. Spell out when using alone, or with a year alone.

Some of you were all over the board in whether to write a number as a digit or a word. Here's the most basic AP guideline, in your style book under numerals: In general, "spell out whole numbers below 10, use figures for 10 and above."

So two should be two, not 2. And 10 should be 10, not ten.

So then, is this correct to start a sentence, under AP Style rules?

Forty . . .

Actually, that IS correct number use. This is under the numerals heading:

Spell out a numeral at the beginning of a sentence.

Now, there are situations where you have a number that would be very awkward to spell out. Like with very large numbers, like 3,158. I would suggest not using such a number at the start of a sentence.Or start such a sentence with attribution so the number conflict doesn't matter (e.g., "According to Izzo, 3,158 ... ) or a generality (e.g., More than 3,000 people ... ).

Is it an eighth-grader or an 8th-grader or an eighth grader?

It's the middle one. AP Style, under grade, grader:

Hyphenate in combining forms: a fourth-grade pupil, a 12th-grade student, first-grader, 10th-grader.

Note there is no exception made from the general AP numbers rule of spell out numbers under 10, and use digits for 10 and above. Also note that the examples given appear to adhere to that rule.

Now, in first reference is it PTA or Parent-Teacher Association? Did anybody look under PTA?