What is least? - 9 or - 15?

-15

Step-by-step explanation:

You calculate least by what is farthest left on the number line.

Whenever you look at any numbers with negative signs, the bigger the number (as long as it's negative) the lesser it is.

Answer:-15

Step-by-step explanation: number line

-15 - 14 - 13 - 12 - 11 - 10 - 9 - 8 - 7 - 6 - 5 - 4 - 3 - 2 - 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15