Regarding the clerk, the use of quotes depends on whether those are the exact words the clerk uses with people or whether that’s the gist of what the clerk says. You may use your discretion as the author.
If the exact words:
The clerk sighed. “That’s why I always tell people, ‘You should never put a bag down without keeping an eye on it, especially in this place.’ ”
If not the exact words:
The clerk sighed. “That’s why I always tell people you should never put a bag down without keeping an eye on it, especially in this place.”
We’re not experts on mathematical notation, so we will answer from a perspective of how these numbers might be expressed most clearly to us. We recommend a hyphen, not a dash, to show number ranges. If you are concerned that a hyphen could be mistaken for a minus sign, then use to . We recommend including the power of 10 with both numbers since omitting it could lead to confusion over what the first number is. Finally, we are more used to seeing ranges expressed from smaller to larger (although your situation may be different). Therefore, we recommend: ×10 9 to ×10 9 .