The abacus is an ancient calculating tool, constructed for the system of powers of ten.
It means, that in lower the column we have the ones place, in the second one we have tens, in the third – hundreds, in the fourth – thousands, in fifth – tens thousands and so on.
The simplest type of calculation you can do – is, if you stay on the ones place and add one number to another, for example 4 plus 3 and we have 7 as a result of your calculation.
If you need to make calculation, that 9, for example 8 plus 7 will be 15. Then you need to calculate it by breaking down 1 bead in the column of tens and 5 beads in the column of ones.
The main idea of the abacus is that tens contains ones, and the hundreds contain tens and so on. And if you have 10 ones you can just break down 1 bead in the column of tens.
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