Lesson Video: Counting in Fifties | Nagwa Lesson Video: Counting in Fifties | Nagwa

# Lesson Video: Counting in Fifties Mathematics

In this video, we will learn how to count objects in groups of fifty and how to count in fifties to 1000.

11:24

### Video Transcript

Counting in 50s

In this video, we’re going to learn how to count objects in groups of 50 and how to count in 50s to 1000. These children are practicing counting in 50s. 50, 100, 150, 200, 250, 300, 350, 400, 450, 500. Why not count along? 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000. They counted in 50s up to 1000. Did you notice any patterns in the numbers as the children were counting in 50s? There’s a hundreds number, a number ending in two zeros, followed by a number ending in 50. This pattern repeats. 900 is a hundreds number ending in two zeros. It’s followed by a number ending in 50. This pattern continues if we count in 50s all the way up to 1000. We have a hundreds number, followed by a number ending in 50.

We can model the number 50 using five tens. If we put two 50s together, we get 100. Double 50 or 50 times two is 100. Two 50s equal 100. Watch how the numbers increase as we count in 50s. 50, 100, 150, 200, 250, 300. As we count forward, the numbers increase by 50, and if we count back, the numbers decrease by 50. Let’s try some questions where we need to practice counting in 50s.

There are 50 coins in each jar. How many coins are there in total? Hint: Count in 50s.

In this question, we’re told that we have to count in 50s to find the total number of coins. This is because there are 50 coins in each jar. Let’s count how many jars there are. One, two, three, four, five, six, seven, eight, nine. If there are nine jars, each containing 50 coins, then we could count in 50s nine times. Let’s use our number line to help. 50, 100, 150, 200, 250, 300, 350, 400, 450. We knew there were 50 coins in each jar. And we counted the number of jars and found that there were nine. We started at 50 and counted forward in 50s. The total number of coins is 450.

The students are counting in 50s. 50, 100, what, 200, 250, what. What number did Amelia say? What number should Ethan say?

In this question, the children are counting in 50s. We need to count in 50s to find the number that Amelia said and the number that Ethan should say because these two numbers are missing. Let’s start at the beginning. The first number is 50. 50 more than 50 is 100. We know that double 50 is 100. So two 50s make 100. To find Amelia’s number, we need to add 50 to 100. 50, 100, 150. The number Amelia said is 150. 50 more than 150 is 200. 50 more than 200 is 250. What is 50 more than 250? It’s 300. The students were counting in 50s. 50, 100, 150, 200, 250, 300. The number Amelia said is 150, and the number Ethan should say is 300. We counted forward in 50s to find the missing numbers.

Find the missing number on the given number line.

We’re given a number line, and we have to find the missing number. The number line starts at zero and ends at 1000. If we start at zero and count forward, we can see the numbers are increasing by 50 each time. And we can see from the green arrows that if we count back, the numbers are decreasing by 50 each time. These green arrows are a hint. They’re telling us that we need to count back in 50s to find the missing number. If we count back from 750, we get to 700. 650, 600. We’re taking away 50 each time. So what is 50 less than 600? 550, 500, and the next number is the missing number. What number is 50 less than 500 and 50 more than 400? It’s 450. To find the missing number, we counted back in 50s. 50 less than 500 is 450. We found the missing number using the number line.

Daniel made trays of five cookies. Count in fives to find how many cookies he made. Five, 10, what, what, what. Hannah bought boxes of 50 cookies. 50, 100, what, what, what. Count in 50s to find how many cookies she bought.

This is a two-part question. In the first part of the question, we have to count in fives to find the number of cookies Daniel made. And in the second part of the question, we have to count in 50s to find out how many cookies Hannah bought. Let’s start by counting in fives. Five, 10, 15, 20, 25. We know that Daniel baked 25 cookies. We counted in fives because Daniel baked trays of five cookies. Five, 10, 15, 20, 25.

Now we need to count how many cookies Hannah bought. Her boxes contain 50 cookies, so we need to count in 50s. We could count in fives to help. Daniel starts with five cookies, which is the same as five ones. And Hannah starts with 50 cookies, which is the same as five tens. Five ones, five tens. 10 ones and 100 is 10 tens. Five, 10, 15, 50, 100. What number comes next? What number is 15 tens? It’s the number 150. The next number in Daniel’s sequence is 20: 20 ones. So the next number in Hannah’s sequence is 20 tens, which is 200. The final number in Daniel’s sequence is 25.

Which number is 10 times greater than 25? It’s 250. 50, 100, 150, 200, 250. Hannah bought 250 cookies. Daniel made trays of five cookies, so we counted in fives to find out how many cookies he made. Five, 10, 15, 20, 25. Hannah bought boxes of 50 cookies. We counted in 50s to find out how many cookies she bought. 50, 100, 150, 200, 250. Counting in fives can help us to count in 50s. When we count in 50s, the numbers are 10 times greater than when count in fives. Daniel baked 25 cookies and Hannah bought 250 cookies.

What have we learned in this video? We have learned how to count in 50s up to 1000. And we’ve also learned that we can count in fives to help us count in 50s because 50 is 10 times greater than five.

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