Assign each group of items a number in order starting with 10.

The number you call the last group of items will denote the total number of objects. 

Back to practice

Here is a thermometer.

You might notice there are more sections than numbers on it, and all the numbers are tens: 10, 20, 30, 40… It is because the thermometer is tiny so that all the numbers won’t fit there. In math such a way of calculating things we call skip-counting.

How can we count all these cubes?

It will take much time to count them one by one. Let’s arrange the cubes by tens and count each set.

Even without counting, we can see that there are 4 groups of cubes. There are 10 shapes in each set. 4 tens equals 40. It means the number of cubes is 40.

We can also apply the method of skip-counting by ten. When counting items grouped by 10 in each set, we assign each group a certain number.

Let’s count shapes. They are grouped by 10s. We call the first set the number 10, the second set the number 20, the third one - 30… We called the last group the number 50. It means there are 50 items in all groups.  

Back to practice