1. The
addition of natural numbers. 
When adding,
we join two values into one.
The
operation of doing sums is also known as addition.
Terms
in the sum are called addends and the result is called the sum.
Solve
these operations by distributing the numbers below to the corresponding
circles.
When you click on the Init button new sums appear.





When
you type the right number it will appear in the window. If the
typed
number is not correct it will not appear.

