The sum of three consecutive odd numbers is -21, how do you find the smallest number?

First things first, we have to analyze the question for clues. The question is: the sum of three consecutive odd numbers is -21, how do you find the smallest number?

Let's take it apart. SUM means addition. So we'll be adding `3` numbers together.

CONSECUTIVE mans that the numbers come right after each other, like `3, 4, 5`.

ODD. Okay, that mans that the numbers have to be odd. So the list would go more like `3, 5, 7`.

The negative in `color(red)(-)21` says that the numbers will be negative, because you cannot add positive numbers to get a negative number, so it has to be caused by negative values.

I think we have all the information now, so let's put it together. I'm going to start by putting in the numbers in order, starting at `-1` and going on from there, skipping the even numbers. So we start out with `(-1)+(-3)+(-5)=`... `-9`. So that didn't work. Let's try with `(-3)+(-5)+(-7)`. This equals... `-15`. Let's try another one. `(-5)+(-7)+(-9)`. This equals... `color(red)(-21)`! We got it! Let's just double check that it meets all the requirements, just to make sure.

Is it `3` consecutive odd numbers that add up to `-21`? Yep, yep, yep, and yep. We're good to go!

So, which is the smallest number out of `-5, -7, -9`? Well, the smallest is the number closest to zero on a numberline, and out of all three, `-5` is the closest to `0`. Great job!