Åk 6–9
 
English/Русский

5.2 Setting up Addition
Setting up addition of the addition algorithm is easy to learn and is greatly simplified when you have mastered the addition  tables. 

The basis for this method of addition is to add the numbers in ones, tens, hundreds, tenths, hundredths and so forth each by themselves. You must therefore also place these under/over each other if  you want to use the model below.


Example A:  44 + 31 = 75

Begin by adding the ones:
4 + 1 = 5


Add then the tens:
4
0 + 30 = 70

The answer becomes seventy five.


Example B:  264 + 373 = 637

Begin by adding the ones:
4 + 3 = 7

 
Add the tens: 60 + 70 = 130

Here you can see that we get the one hundreds and three tens (100 + 30 = 130) and therefore write the number 1 above the hundreds in order to show that it is carried over.

 

 
Add hundreds and the carried number:
1
00 + 200 + 300 = 600

The answer becomes six hundred and thirty seven.


Example C: 38.8 + 5.74 = 44.54

Here it is important how you write out your numbers when setting this up.  Hundredths, tenths, ones and tens should be over/under each other.  Think about  38.8 and 38.80. Try to enter “38.80=” in your calculator. What answer does it give you?


Add the hundredths: 0.00 + 0.04 = 0.04



Add the tenths: 0.8 + 0.7 = 1.5 and carry over the 1.

Don’t forget the decimal!



Add the ones and carry the 1: 1 + 8 + 5 = 14




Add the hundreds:
1
0 + 30 = 40


The answer becomes forty four and fifty four hundredths.