Arithmetic (all content)
- Adding 2-digit numbers without regrouping
- Adding 2-digit numbers without regrouping 1
- Example: Adding 2-digit numbers (no carrying)
- Adding up to four 2-digit numbers
- Breaking apart 2-digit addition problems
- Break apart 2-digit addition problems
- Regrouping to add 1-digit number
- Regroup when adding 1-digit numbers
Adding Whole Numbers and Applications 1. Created by Sal Khan and Monterey Institute for Technology and Education.
Want to join the conversation?
- What happens when you DO have to carry?(6 votes)
- 1 you just put the carried number over the next digit and add it like it is a reg numba
- Is there a way that you can show in this demonstration base-ten strategy as well as the expanded form and whole number?(3 votes)
- is there an easier way to add?(1 vote)
- Using a number line might help. The problem with that is when you get to bigger numbers you'll be counting forever. Adding gets easier the more you do it. Doing a few problems on your own until you get it down would help immensely.(2 votes)
- how do you add the digits? Isn't it sometimes hard doing it mentally?(1 vote)
- it is very simple doing it mentally.for ex. 30 + 50 = 80 we just have to add 5 to the tens place(2 votes)
- how do you borrowing 3 digits numbers(2 votes)
- Why does the guy keep repeating what he says(1 vote)
- to make sure we heard it the first time or maybe he says it back to himself to make sure he didn't make any mistakes(1 vote)
So we need to figure out what 46 plus 43 is. Let me write it down again and I'll write it like this: 46 plus 43. What we do here is we just first look at the ones place. We literally have 6 ones plus 3 ones, or you could say 6 and 3, and 6 plus 3 is just 9. 6 plus 3 is 9, so we have 9 ones. And then you go to the tens place, and there's two ways to think about it. You could view this as 4 plus 4 is equal to 8, but really, the reality of what we're doing since we're operating in the tens place, this is really 40 plus 40 is equal to 80. And we could do the same problem expanded out. This is the same thing as 40 plus 6. We've seen this before, right? That's what 46 is. And then 43 is the same thing as 40 plus 3. We've expanded these out before. And so when you add them, when you add a 6 plus a 3, you get a 9. When you add a 40 plus a 40, you get an 80. So you get 80 plus 9, which is 89. And the whole reason why I did this is I wanted to show you that when you're adding 4's in the tens place, you're really adding 40's. The fact that it's in the tens place represents-- or the fact that the 4 is in the tens place shows that it represents 40. The fact that the 8's there shows that it represents 80.