Counting by tens | Counting | Early Math | Khan Academy

So we are told, let's count by tens, and we go 10, 20, blank, 40, 50, 60, 70, 80, 90, 000. What number did we miss? Pause the video. What number did we miss right over here? Well, if we're counting by tens, we would go 10, 20, 30, 40, 50, 60, 70, 80, 90, 100. So we're missing 30.

So which choice right over here has 30? Well, if we scroll down a little bit, we see right there that is our choice. Let's do another example. So here we are asked, which 10 frames show 20? A 10 frame is just a fancy word for one of these blocks of these frames that have 10 objects in it. You can see it right over here: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

So which of these 10 frames show 20? Well, 20 is two groups of 10. So this is 10, and then 20. So that's 20 right over there. Choice B is 10, 20, 30, 40. Choice C is 10, 20, 30. So we could feel good about choice A here.

We're told drag the 10 frames into the box to make 40. So let's see here: this is 10 right over there, then we get another 10 gets us to 20, then another 10 gets us to 30, and then finally another 10 gets us to 40. 10, 20, 30, 40. We're done.