Week 1 Video
Week 1 Transcript
Today we are going to learn how to add 2 digit numbers. When we are adding we are combining two or more things. We have learned how to add one digit numbers like 5 plus 4. Today we are going to learn how to add numbers that are a little bigger. Let's start with this adding situation.
Destiny has 23 Valentine's Day cards. Her sister Karla has 25 cards. How many cards do they have in all?
We know that we need to add 23 and 25.
Before we begin let's review place value. 23 has a 2 in the tens place and a 3 in the ones place. 25 has a 2 in the tens place and a 5 in the ones place. As mathematicians, we can't add units and rods together because they are not the same thing. They are different. So we have to make sure that we line up our units and we line up our rods. Then we can add them together.
Now we are going to start with the ones. We know that 5 plus 3 equals 8. Now let's move to the tens. We know that 2 plus 2 equals 4. Our sum is 48. Destiny and Karla have 48 Valentine’s Day cards all together.
Let's try one more example:
Jaelen has 14 Sonic comic books. Elijah has 12. How many do they have in all?
Don’t forget we need to line up our tens and ones. Jaelen has 14 comic books and Elijah has 12. Now let’s solve. First we start with the ones. 4 plus 2 equals 6. Now let's move to the tens. 1 plus 1 equals 2. That means our sum is 26. Jaelen and Elijah have 26 comic books all together.
Great work! Now you know how to add 2 digit numbers.
Week 2 Video
Week 2 Transcript
Today we are going to learn what happens when the sum of the ones is greater than 10.
Destiny has 26 cards and her sister Karla has 35 cards. How many cards do they have in all?
First, I line up my addends. 26 plus 35 equals. Next, I start with the ones. 6 plus 5 equals 11. However, 11 is not a number made completely with units. I know that 11 has one rod and one unit. I know that I have to keep my rods and units separate. So I am going to leave one unit in the ones place and move one rod in the tens place. This is called regrouping. Now I am ready to add the tens.
2 plus 3 equals 5, but wait a second, I know that I have a 1 that I regrouped from 11. 2 plus 3 equals 5 plus 1 more equals 6. My sum is 61. Karla and Destiny have 61 cards.
Now lets try another example. Jaelen has 48 comic books. His friend Elijah has 23 comic books. How many comic books do they have in all?
I know that I need to add so I am going to go ahead and line up my addends. 48 plus 23 equals. I know that I start in the ones place. 8 plus 3 equals 11. Oh no! I know that I can’t put a rod and a unit in the same spot. So I’m going to regroup. 1 goes in the units and 1 goes in the rods place. Now I can move to the tens place. 4 plus 2 equals 6, but I can’t forget about the 1 I regrouped. So 6 plus 1 equals 7. The sum is 71. Jaelen and Elijah have 71 comic books.