**High School Number Sense Lesson 1: Adding whole numbers**

Adding whole numbers is one of the most basic concepts in mathematics. You might be asking, "

*Why is this a high-school level concept?*" Well, because this concept showed up 15 times on the 21 high school tests this year--11 of those times as question #1 (+3 times as question #2 and once as question #3). So we'll cover this now and move on to more challenging stuff!

**Number Dojo Level: 4**

**How to add whole numbers:**

- Pay close attention to the place values--especially if the addends (the numbers you are adding together) have a different number of digits.
- Work from right to left within each addend. Add the ones digits from each number. If the sum is <10, write it down to the right. If the sum is 10 or greater, write the last digit of the sum and regroup the 1 with the tens digits.
- Move left to the tens digits, adding them together and including your regrouped 1 (if any).
- Repeat this process with the hundreds digits, etc.

**Example 1: 327 + 916**

- Start with the units: 7 + 6 = 13. Write the
**3**and regroup the 1 with the tens digits. - Then add 2 + 1 = 3. Add the regrouped 1 and write down
**4**to the left. - Then add 3 + 9 =
**12**; write this in front. The answer is**1243**.

**Example 2: 2016 + 531**

- Start with the units. 6 + 1 =
**7**; write it down. - 1 + 3 =
**4**; write this down to the left. - 0 + 5 =
**5**; write this down to the left. - 2 (+ 0) =
**2**; write this in front. The answer is**2547**.

**Example 3: 867 + 5 + 309**

- Start with the units. 7 + 5 + 9 =
**21**. Write the**1**and regroup the 2 with the tens digits. - 6 (+ 0) + 0 = 6. Add the regrouped 2 to get
**8**. Write this down to the left. - 8 (+ 0) + 3 =
**11**; write this in front. The answer is**1181**.

**Example 4: 13579 + 24680**

- Start with the units. 9 + 0 =
**9**; write this down. - 7 + 8 =
**15**. Write the**5**and regroup the 1 with the hundreds digits. - 5 + 6 (+ 1) =
**12**. Write the**2**and regroup the 1 with the thousands digits. - 3 + 4 (+ 1) =
**8**; write this down. - 1 + 2 =
**3**; write this in front. The answer is**38259**.

**Here's a free worksheet to help you practice AddWhole:**

addwhole.pdf |

**Up Next: SubWhole**