Why is it important to line up the addends by place value when adding two numbers?

So you will be sure to add the digits in the same place value together.

2717: the digit in the hundreds place, 7, is greater than 5, so you round up to 3000.

222: you round to the nearest hundred, so look at the digit in the tens place. 2 is less than 5, so the hundreds place stays the same. 222 rounds to 200.

28 = 7 x 4 : 28 is 7 times as many as 4.