You will need to have a strong understanding of place value to be successful when adding numbers. The value of each individual digit is crucial to your understanding in both adding and subtracting. There are multiple strategies involved with addition, however, the first practice is going to be estimation. Take a look at these two numbers… 649 and 202. After hearing these two numbers stated let’s work through a way that you can perform mental math. The value of the 6 in 649 is 600 and the value of the 2 in 202 is 200. The value of the 4 in 649 is 40 and the value of the 0 in 202 was 0. The value of the 9 in 649 is 9 and the value of the 2 in 202 is 2. Remember, the answer to an addition problem is called the sum.
Try Performing mental math this way:
649 and 202
600 + 200 = 800
40 + 0 = 40
9 + 2 = 11
Your sum would be 851.
Another strategy that can be used to add these two numbers would be a number line. A number line serves as a visual representation in which you add the numbers together. Let’s use the same numbers as we did previously, 649 and 202. Take a look below, the larger jump represents 200 and the small jumps represent 1’s.
Another important component of adding is estimating and rounding. Let’s continue using the same numbers but estimate an answer. Follow along with me as I think aloud…
If you have a digit that is 5 or higher, round up. If you have a digit that is 4 or lower, round down.