 # To @Zed_Girl. How ADD and SUBTRACT fast

First, you must know what is ENDING NUMBER

7 + 6 = 13

Do you notice this addition end in 3? This is called ending number.

8 + 7 = 15

Do you notice this addition end in 5? This is called ending number.

You must know to begin with addition all the ending numbers, and it’s a very very easy task to do. Only with practice you will memorize these features.

So, if I ask you the ending number of 8 + 9, 4 + 7 or 5 + 6 you should anwering very fast respectively 17, 11 and 11.

Practice as much as you could Zahra.

For example, 38 + 17.

Do you see that 8 + 7 is 15? That the ending number is 5? This means that the units sum is an amount higher than 10, right?

That’s why we have carry.

STARTING with the TENS 3 + 1 + 1 from the carry, we have 5, and from the ending number of the UNITS, we have 5 too. The answer is, then, 55.

Another example: 16 + 48

Do you see that the amount of units are higher than 10? Than 6 + 8 is 14? That 4 is the ending number and that we have a carry?

Then we start from the left, from the TENS: 1 + 4 + 1 from the carry give us 6.

6 in the TENS and 4 as ending number of the UNITS. Then we have 64 as the answer.

Feel free to ask whatever question if you don’t understand @Zed_Girl

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