Guess how many shapes are in each illustration. Round the number to the nearest ten.

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Look at the picture. Can you say how many beads are in each jar?

We know there are 50 beads in the small jar. But how many are in the big one? We can see the big jar is 2 times greater than the small one and isn’t completely filled. Can you estimate how many beads there are? Maybe 10? No. 10 is less than 50, and we know there are more items in the big jar than in the small one. Then maybe 1000? No, it’s too much. How to find it out? Let’s try to estimate. Maybe there are no more than 100 because we can see the big jar is 2 times greater than the small one, and there are 50 beads in the small jar. There are likely less than 100, as the big jar is not completely filled. So, maybe there are 70 or 80 beads.

We estimate when we cannot establish the exact number. For example, we cannot count flowers in the field, as there are too many as in the picture.

But we can assume. What will help us? The fact that the stars are arranged in the row. We may guess how many stars are in one row - may be about 10. Even without counting, we can say there are 5 rows with shapes. How many objects are in total if there are 5 rows with 10 items in each? These are 5 tens, that is 50. So, there are approximately 50 stars. We can also see 3 stars below, but we don’t need the exact number, so we round 53 to 50, as it’s easier to count from 53 to 50 than to 60.

What shall we do if there are more than 5 stars in the lowest row?

There is one missing star up to ten in the lowest row, which means there are 9 items. These are almost 6 rows with 10 shapes, that is 6 tens. We round 59 to 60 and estimate there are approximately 60 stars.  

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