Adding and Subtracting One-Digit Numbers

Example : 1 + 2 = 3

Step 1: Set the number 1 by moving up one 1-unit bead with the thumb. See that you set 1 on a unit rod marked with a unit point.

Step 2: Add 2 to 1 by moving up, on the same rod, two more 1-unit beads, using the thumb.

Note 1 : This example illustrates the procedure used in adding one or more 1-unit beads. The problems to which this procedure applies are:

1+1
2+1
3+1
5+1
6+1
7+1
8+1
1+2
2+2
5+2
6+2
7+2
1+3
5+3
6+3
5+4

Note 2 : Hereafter, such phrases as “move up one 1-unit bead,” “move down three 1-unit beads,” etc., will be shortened to “set 1,” “move down 3,” etc.