Fun with Numbers Chapter Notes | Mathematics for Class 2 (Joyful-Mathematics) PDF Download

What are Numbers?

• A number is a value used for counting and calculating.
• Numbers can be shown in different ways: as words (one, two, three) or figures (like 1, 2, 3).
• There are different kinds of numbers based on how many digits they have.

• Single-digit numbers have only one digit, like 1, 2, 3, and so on.
• Two-digit numbers have two digits, like 10, 25, 99, and so on.
• Three-digit numbers have three digits, like 100, 345, 897, and so on.

Now, students, can you count how many flowers there are?

By counting these, we can see that there are a total of 36 flowers. 

Step Counting

Let us now read an interesting story!

Once upon a time, there was a little kangaroo named Skip who loved counting. But regular counting bored him. So, he invented step counting! 

Instead of going one by one, he jumped ahead or backwards by a special number each time.

His friends loved it, and soon, everyone in the jungle was step counting their way through numbers, making counting fun and fast!

What is Step Counting?

• Step counting means counting numbers by adding the same amount each time. Instead of going one by one, you skip ahead by a certain number each time. It's a great way to count big numbers quickly or make cool patterns with numbers.
• Backwards skip counting is like counting in reverse. Instead of going forward, you start from a larger number and subtract a certain amount each time to reach the next number. It's just like walking backwards but with numbers.
• Now, let us play the game of step counting and see how this is done.

Forward Step Counting

Let us understand how to skip count. 

Skip count by 2

• Start at zero, then continue to add 2.
• 0+2 = 2. So now from 0, we have reached 2.
• Now we will again add 2 in the number 2. 
• 2 +2 = 4
  
• Now that we have reached 4, we again add 2.
• 4+2=6
• Now we again add 2 in 6
• 6+2= 8
• Continue this process until you reach 12. 
• We have represented the same on the number line. 

• You can skip count starting at any number.
• For example, skip count by 2 starting at 5.
  
• 5, 7, 9,11, 13…

Skip count by 5

• In skip counting by 5, we add 5 in each number and move forward. 
• Students, let's play a tough game. 
• What numbers will the kangaroo reach if he starts from number 5 and skips by 5?
• We have done the same for you on the number line given below.

• Skip, the kangaroo, will start from 5, then reach 10, 15 and 20. 
• 5 +5 = 10, 10+5=15, 15+5=20

Skip Count by 10

• Let us play another game.
• The kangaroo is shown skipping ahead in this picture. Can you complete the pattern by looking at the picture? 

• How can you find out the pattern?
• We can see that the kangaroo first jumps from 0 to 10. Then 10 to 20.
• We will use the method of subtraction here to find the pattern and then complete the series.
• We will first subtract 10 from 20. 20-10= 10
  
• Now, 10-0= 10.
• We can see that the difference is of 10. 
• Hence, to complete the series we need to add 10 to each number and move forward.
  
• The complete series will be: 0, 10, 20, 30, 40, 50, 60, 70, 80, 90,100.

Backward Skip Counting

• What we have learned so far is called forward skip counting, which implies we are counting in the forward direction and adding a certain number to each previous number to obtain the next number in the series. 
• Now, we will discuss backward skip counting. 
• Backwards skip counting is a way of counting numbers in reverse order by skipping a certain amount each time. Instead of starting from a lower number and counting up, you start from a higher number and count down. For example, if you're skip counting backward by 3s from 10, it would go like this: 10, 7, 4, 1. 

Backwards Skip Count by 3

• To do so, we subtract 3 from each previous number to obtain the next number in the series. Suppose we start with the number 100, so to obtain the next number in the series, we subtract 3 from it. 100 - 3 = 97. Continuing in the same manner, we have
• 97 - 3 = 94
• 94 - 3= 91
• 91 - 3 = 88, and so on.
• So, the series obtained looks like 100, 97, 94, 91, 88 and so on.
  
• Here the numbers are in descending order.

Backwards Skip Count by 20

• Let's imagine we're on a backwards adventure, counting by 20s. Instead of walking forward, we're taking big jumps backwards, like going down a staircase in giant steps.
• So, let's start at a big number, like 100. Now, instead of counting down by 1, we're going to count backward by 20. It's like taking a step back in time, but in numbers!
  
• 100 (start)

  80 (we took one step back, like a giant leap!)
  60 (another big step backward)
  40 (we're really moving now!)
  20 (almost there!)
  0 (and we've reached the end of our backward journey!)

Guess My Place

• Now, let us play an interesting game in which we have to guess the place of the ants.
  
• Look at the number line, and answer the following questions:
  (a) Which number is the red ant sitting on?
  (b) Which number is the blue ant sitting on?
  (c) Which number is Brown Ant sitting on?
• To answer these questions, let us first fill the number line with numbers.
• Since we have to go from 10 to 110 and have 9 places to fill, let's take a guess and fill them up with the gap of 10. 
• So, 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 110.

• Answers:
  (a) Red ant is sitting at number 20.
  (b) Blue ant is sitting at 50.
  (c) Brown ant is sitting on number 90.

Exploring Patterns

Q: Look at the number chart and write down the answers.
__9___ comes just before 10
__19___ comes just before 20
__29___ comes just before 30
__39___ comes just before 40

What is the pattern here?
Ans: Let us subtract 19-9 = 10
29-19 = 10
39-29 = 10
We can clearly see that the difference is of 10.
The pattern can be completed: 9, 19, 29, 39, 49, 59, and so on...

Q: Now, look at the numbers coloured purple in the number chart. Write them.

7, 16, 25, ____, ____, ____, ____, ____, ____, ____

Ans: 7, 16, 25, 34, 43, 52, 61.

Q: What is the pattern?

Ans: The difference is of 9.
9 has been added to each number.

Look at this fun number window.

Now, using this concept, we will move forward to a fun game 

Fill in the blocks given below:

Now, observe how these blocks are placed on the basis of the number given and extend the pattern further.

To find the block above 55 we have to subtract 10 from 55, which gives us 45.

To find out the block below 55, we need to add 10 to 55, which gives us 65.

Now, moving on to the above row, we have found the middle block, which is 45. To find out the block on its left, we need to subtract 1 from it.
45-1 = 44
To find out the number on its right, we need to add 1 to 45 which gives us 46.
Similarly, we find out the numbers in the last row.

Let's look at some more examples of numbers grids:

1. 

Using the same logic as above, let's add numbers to this grid:

2. 

Let's fill up this magic grid:

Hope you enjoyed playing with numbersand exploring different games. Keep practicing and having fun!