Expanded form of a number is another way of writing out what it is. For example: 24 is 20 + 4. Another example: 111 is 100 + 10 + 1. Hopefully you see a pattern here. Now, looking at 879, we see that there is an 8 in the hundreds place, 7 in the tens place, and 9 in the ones place. Once again, we're just trying to represent the number through addition. So the answer is:
