Correct usage of numbers in essays

According to the Associated Press Style Book:
" Spell out first through ninth when they indicate sequence in time or location: first base, the First Amendment, he was first in line. Starting with 10th use figures.

Use 1st, 2nd, 3rd, 4th, etc. when the sequence has been assigned in forming names. The principal examples are geographic, military and political designations such as 1st Ward, 7th Fleet and 1st Sgt.

In general, spell out whole numbers below 10, use figures for 10 and above. Example: They had a fleet of 10 station wagons and two buses."

Also, specifically for millions and billions, it says to use figures in all except casual uses. "I'd like to make a billion dollars." But: The nation has 1 million citizens. I need $7 billion."

Ok how about the scenario where I need to discuss two figures in the same context, one below 10 and one above 10. I feel its more consistent to either spell both or use figures for both ?

e.g.
Initially I thought I had lost five percent, however, my real loss was 15% ?

I am not an expert, haven't submitted any apps yet. So it might be just my opinion.
But there is no way a reasonable person will give weightage to the fact that you are writing "Five" in place of 5.

I read that you should spell out numbers up to two words so that basically covers all numbers through one hundred. I don't think it will matter as long as you are consistent.

So, let me understand... Your essays goes something like this?

Since My net worth is 13 million dollars, I was 20 when I started working fulltime. Let me tell you: Rule number 1: dont date someone at work!. As a result, Me and my team of 5 were sacked. Even if I have done this for 20 years!

Makes a great mistakes essay, doesn't it?

I've always done the exact opposite...

Either way, I don't think anyone will give it a second thought.

The most important thing is to be consistent. Pick a way and go with it.

Really, after 6 months in business school, the finer points of writing seem low on everyone's list of priorities.

Yar.

That does explain my dings so far