Addition of natural numbers is very simple. We add them like we add objects so final results are independent of the how we do it. Addition of numbers expressed in decimal system is simple and can be more efficient by making addition in groups acordingly to the system.
Generally off course the order of adding numbers does not matter.
In practis adding objects for example does not recquire any special ruls. It does not matter how they are placed all together except they are create one set but if the question "How many ? " arise we have to group them or count them then use our symbolic method of expresing quantity. It means that to answer this question we have to make order phisycaly or mentally with our set.
We know that to expres quantity in our decimal system we have to group object by tens, hundreds, thousants etc. What is remaining are units. While adding numbers to keep better order we add similar groups first.
It is easier than to put them in order.
Our exercise two numbers to be added are shown as two sets of objects.
The computer does not allow you to add different decimal groups so the rules of adding those objects are identical as to the rules off adding decimal numbers.
the bills are arange in figures in order to recognize the related quantity. The groups can be moved by draging and dropping with a mouse Rysunki można przesuwać. You can join similar groups by puting one over an other.
Enjoy!
designed by Witold Wojcik