The construction of Russian stchoty

Common Russian stchoty consists of wooden frame and 10 to 13 iron rods with ten wooden or plastic beads each. But one or two rods in the lower part of the frame have only four beads. These incomplete rods are for calculation with fractions (1/4 parts of quantities). Moreover, they mean decimal point. The beads are black, but usually the 5th and the 6th beads in complete rods and the 2nd and the 3rd beads in incomplete rods are colored in white. The frame is placed so, that the rods are lying horizontally. The initial position of the beads is the right end of the rods.

And now three very simple examples.

Example 1. Display the number.

Example 2. To add: 3,25 + 4,31 + 5,77 = 13,33

Display the first number

Move
1 beam to the left (hundredth rod)
3 beams to the left (tenth rod)
4 beams to the left (units rod)

Intermediate result 3,25 + 4,31 = 7,56

Move
4 beams to the left (hundredths rod)
Then 1 beam to the left (tenths rod), all 10 beams to the right and again 3 beams to the left (hundredths rod)

Move
4 beams to the left (tenths rod)
Then 1 beam to the left (units rod), all 10 beams to the right and again 3 beams to the left

Move
2 beams to the left (units rod)
Then 1 beam to the left (tens rod), all 10 beams to the right and again 3 beams to the left (units rod)

Final result 13,33

Example 3. To subtract: 7,58 - 3,21 - 2,48 = 1,89

Display the first number

Move
1 beam to the right (hundredths rod)
2 beams to the right (tenths rod)
3 beams to the right (units rod)

Intermediate result 7,58 - 3,21 = 4,37

Move
7 beams to the right, then 10 beams to the left and 1 beam to the right (hundredths rod)
1 beams to the right (tenths rod)
2 beams to the right, then 10 beams to the left and 2 beam to the right (tenths rod)
1 beam to the right (units rod)
2 beams to the right (units rod)

Final result 1,89