How should you handle numbers or confusing jargon in dialogue?

Numbers and jargon in dialogue should usually be spelled out in full, and as specifically as possible. If not, you run the risk of your actor saying something different than you intend.

If you writer your scene:

MARY

How much is the bill?

SHOP OWNER

$1,329.00

We don’t know who this shop owner is, or how the actor portraying him is supposed to deliver that line.

Better would be:

SHOP OWNER

One-thousand three-hundred twenty-nine dollars.

Or:

SHOP OWNER

Thirteen-hundred’n twenty-nine.

Or if he’s robotic:

SHOP OWNER

One three two nine and zero cents.

With dates, phone numbers, addresses, and codes, it’s generally okay to use the numbers themselves. But if you want a specific reading, it is always safer to write it out.