Bài 9: Addition of two digit number

Starry, this is a nice board, we can write or draw on this board with a marker.

Come on, let us learn addition of two digit number using this board.

See I have already draw square of 100 on this board.

Let us now see how to add 25 and 6. Yes yes Starry, the method it the same.

Using the square of 20. First we put this magic coin on the number 25.

Now move the coin ahead six squares in the same and next column. 1 2 3 4 5 6.

Which is square do we read Starry? Yes, 31. So 25 plus 6 equal 31.

Do you understand Starry? Ok, then let’s solve the next example, 57 plus 9.

Here let’s put the coin on the number 57. How many square do we have to move ahead?

Yes, 9 squares. Here we have read the number 66.

So, we can say that 57 plus 9 equal 66.

This is a lot of fun!!! Ok, now let’s look another example.

It is 5 add to 81. Where we should put the coin Starry?

Yes, we start from the square 81, now let’s move the coin ahead. 1 2 3 4 5.

That’s 81 plus 5 equal to 86. I know what are you thinking Starry.

You aren’t worry. This square can be use for adding two digit number.

This will take along time. For example if we have to add 82 to 16.

Then you know what we have to do Starry?

Yes, we have to move the coin 82 square ahead of 16.

This will take along time. So let’s use another method to do addition.

16 plus 82. First we will arrange the numbers in vertical and solve.

Write 1 in the tens place and 6 in the units place.

Next, let’s place 8 below 1 in the tens place and 2 below 6 in the units place.

First we shall add the digit in the units column 6 plus 2 equal to 8.

Next we have to add the digit in the tens place, we get 1 plus 8 equals 9.

So Starry, 16 plus 82 equals to 98. It is a more fast the method Starry!

Ok, now let’s solve the next example. Add 23 and 61. What shall we do first Starry?

We shall first arrange the numbers in proper column.

In the number 23 write 2 in the tens column and 3 in the units column. What about 63 Starry?

Yes, we write 6 below 2 in the tens place and 1 below 3 in the units place.

Now let do addition! 3 unit plus 1 unit equals to 4 unit.

2 tens plus 6 tens equals to 8 tens. So, 23 plus 61 equals to 84.

Let’s solve the next example. 40 plus 12.

We shall first arrange the numbers vertically and solve.

Now Starry, carry out there addition.

Yes, on adding digit in the units place, we get 0 plus 2 equal 2 unit.

Next 4 tens plus 1 tens equals to 5 tens. So what answer do we get Starry?

Yes, 40 plus 12 equals 52.

Remember Starry, it is not necessary to make columns for the tens and the units place to do addition each time.

But, it is necessary to write the digit in the correct places.

Let’s solve one example. Add 35 plus 52.

First we shall write the number 35, next 52 below 35 exact a way that 5 is written below 3 and 2 below 5.

Let’s add the digit in the unit place first. So 5 plus 2 equals 7 units.

Next to be add the digit in the tens place. So what is answer Starry?

Yes 3 tens plus 5 tens easy equals to 8 tens. So 35 plus 52 equals 87.

In the next example add 7 and 31. Arrange numbers vertically and solve.

Starry, do you know what be the answer it? 7 units plus 1 unit equals 8 units.

3 tens is written in the tens place. So 7 plus 31 equals 38.

Here the last example. Numbers here have been a ranked vertically.

How much is 22 plus 55 equals to?

Yes Starry, 2 units plus 5 units equals 7 units, 2 tens plus 5 tens equals to 7 tens.

So 22 plus 55 equals 77.

So Starry, remember when using the vertical arrange to add place of the digit very important.