Bài 8: Even and odd number (part 1)

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Hey Stary! Look. Here is a box of pencils. There are 10 pencils in this box.

Let us form pairs. 
That is group of 2 pencils each for both of us .

Here it is 1st pair, 2nd pair, 3rd pair, 4th pair and 5th pair.

Is any pencil left behind Stary?

No? Stary! no pencil is left behind after making groups of 2 each from 10 pencils ,

so 10 is known as an even number.

Don’t you think we also need erasers along with these pencils?

Yes, see. I have got a box of erasers too.

But it has only 7 erasers. Let us see Stary! How many pairs are formed.

Here they are 1st pair, 2nd pair, 3rd pair.

Look Stary !1 eraser is left by itself.

So we say that 7 is an odd number.

Stary, if one object is left over after pairing then the number of objects is odd.

If no object is left after pairing, then the number of objects is even.

Look at this number square Stary. Number from 1 to 20 is written in it.

now, Starting from 1, circle every odd number.

So let circle the number 1, 3, 5, 7, 9, 11, 13, 15, 17 &19 .

Stary! Can we form a pair with 1 object? you’re right we can’t form a pair with 1 object.

Now let us consider the next circle number that is 3.
uhm.

Here are 3 chocolates, Stary! Can you form pair with it?

yes, only 1 pair is formed , &1 chocolate is left by itself.

So Stary the 3 is an odd or even number?
Yes, 3 is an odd number.

See Stary, the remaining circle number has been written here.
lines equivalent to the number are also drawn.

Consider the number 5. Let’s form the pairs of line.

Here 2 pairs are formed and 1 line is left by itself.

What’s about the number 7 stary? 
Yes! Here are 3 pairs are form and 1 line is left by itself.
Similarly we observe that is odd the number 9, 11, 15,17& 19 .

1 line is left behind.

Can you tell me what is common in all the number?

Yes, all the number 1, 3, 5, 7, 9, 11, 13, 15, 17,19 are odd numbers.

Now Stary, list these number which are not circle.

Yes, the numbers are 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 .

How many pairs are formed with 2 object, Stary? Yes, only 1 pair.

Which is the next number, Stary? Yes, it is 4.

Let’s see ! what do we have here? Yes, here we have 4 crayons .

Can you tell me how many groups of 2 crayons will be form?

Yes, 2 pairs are form and no crayon is left by itself.

So we can say that 4 is an even number.

Hey! Stary, it’s time to look at the other number.

The number is written here is 6. let us form pairs with 6 sticks.

Can you count the number of pair Stary,

yes 3 pairs of sticks are formed and no stick is left behind.

so 6 is an even number.

Observe carefully Starry! when we form pair of sticks with number 8, 10, 12, 14, 16, 18 and 20 no sticks are left behind.

So we now know that the number 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 are even numbers.

Stary! It is not possible to form pairs of objects everytime to decide if a number is odd or even.Here is a nice idea.

If the number 1, 3, 5, 7, or 9 are found in the unit place of the numbers,

then they are called odd numbers.

If the number 2, 4, 6, 8 or 0 are found in the unit place of the numbers,then they are called even numbers.

I’m sure you are can now easily identify odd & even number.

Ok! Then let us saw a few example.

Here are some numbers.

Can you identify which one are odd and which one are even numbers?

Let’s start with number 21.

It has a digit 1 in the unit place so 21 is an odd number.

Number 38 has 8 in the unit place so it is an even number.

In the number 43 the digit  in the unit place is 3,so 43 is an odd number.

The next number is 57. 
Will it be odd or even number, Stary?

Yes since the digit in the unit place is 7,  57 is an odd number.

Similarly we see that the number 64, 70, 96 and 58 are even numbers and they have 4, 0, 6 and 8 in their unit place.

Stary we are now left with the number 89 and 25 .

The number 89 and 25 are odd as they have 9 and 5 in their unit place.

Now let us saw the next example.

Stary fill in the missing odd numbers in this strip.

The odd number given are 33, 37, 41, 49 so which are the missing odd numbers .

Yes they are 35, 39, 43, 45 and 47.

The next example is simple , Stary.

we have to write 10 consecutive even number after 62.
Come on write fast.

Yes, 64, 66, 68,70,72, 74, 76, 78, 80, 82.

Stary remember we can easily find out whether a given number is odd or even by observing the digit in its unit place.

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