Sal counts by 10s.
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- at0:13and0:40he said 40 50 60 70 80 90 but those numbers are counting by 10's.Why don't we just add 1 at the tens place , then put a 0 at the ones place.Isn't it easier to do now ? -_-(10 votes)
- Skip counting by tens is basically adding one to the tens place. When you need to add 10 to, say, 290, you need to change the hundreds too. But you are right! Sal made this to give more practice to kids who might not grasp this as easy as you did :)(7 votes)
- Count by 10s starting with 40. Fill in the blanks. So, let's count by 10s, starting with 40. So, 40 is four 10s. So, if we add 10 to that, we're gonna get five 10s, or 50. Now, if we add 10 to that, we're going to get six 10s, or 60. Now, if we add 10 to that, we're going to get seven 10s, or 70, but we don't have to type that in, because they've already put that there for us. Let's keep adding 10s. So, if we add 10 to 70, or 10 to seven 10s, we're going to have eight 10s, or 80. Add 10 to that, you're going to have nine 10s, or 90. And then we're done. Let's do one more of these. Count by 10s starting with 656. Fill in the blanks. Well, each time we want to add one 10. So, this 656, it's six hundreds, five tens, and six ones. Well, now we're going to add 10 to it. So instead of having five 10s, we want to have six 10s, so it's gonna be 666, six hundreds, six tens, and six ones. Let's add 10 again. Well, now, in the last one, we had six 10s, now we want to have seven 10s. So, it's gonna be 676. Now, let's add another 10. Well, now we're gonna have six hundreds, eight tens, and six ones, or 686. Now, let's add 10 again. So, now, we're gonna have six hundreds, instead of eight 10s, we're gonna have nine 10s, and six ones. So, 696. Now, the next one is going to be interesting. We want to add another 10 to this. But how do we have, if we add another 10 to this, what do we have in the tens place? Well, one way to think about this is, you can view six hundreds and nine tens as 69 tens. So if you have 69 tens, and you add one more ten, you're going to have 70 tens, so you're going to have 70 tens, and six ones. So, 696, you add 10 to it, you get 706. Once again, you can view this as 65 tens and six ones, So, 65 tens, 66 tens, 67 tens, 68 tens, 69 tens, and 70 tens. 706.