# 25. Teaching timing for the Nine-bead calculation.

Updated: Dec 11, 2020

What is nine beads? It is also a kind of abacus teaching aids. The abacus tools used by countries around the world to promote abacus education are all "one four bead" abacus. Compared with the "two-five-bead" abacus used by traditional Chinese in the past, the history of the nine-bead abacus may be earlier. The earliest formation of the abacus was not the existing Japanese abacus one-four beads in the decimal system, nor the traditional Chinese abacus two-five beads in the two-pound system. It is a simple decoration composed of various objects such as shells, stones, copper coins, wood, etc., and gradually forms fixed tools and calculators with the evolution of the times.

Ten beads and nine beads are the early abacus that evolved. At that time, the concept of decimal was already in place. Later, with the improvement of the abacus of 2, 5 beads and 1, 4 beads, ten beads and nine beads were retired, so they were less used and paid attention to. 1, 4 beads has been widely reused in the past 100 years, in addition to complying with the decimal system, because the beads reduce the frequency of shortening the movement of beads, save the calculation time, and also achieve the same effect in the use of mental arithmetic. But the learning of 1, 4 beads is a potential pressure on the cognitive ability of young children. Because it has to recite and understand the five-complement formula and meaning. Some students lose their interest in learning because they cannot fully understand the use of 5 and 10 complements. Therefore, the rebirth of ten or nine beads is triggered.

Ten beads is one more bead than nine beads, which also means that one more step is required to have a process of ten or ten retreats. Since the calculation methods of the two are the same, of course, ten beads are used to take nine beads. The advantages and disadvantages of 9 beads are exactly the opposite of 1, 4 beads. Its advantage is that there is no five-complement combination, only the original decimal; there is no need to learn the complicated 5-complement addition and subtraction and mixed 10-complement addition and subtraction, only need to learn the 10-complement in the same way as the school mathematics calculation, it is easier It is practical, but the disadvantage is that it requires more beads to be remembered and operated when used in mental calculations, which is more time-consuming and difficult to create images. Therefore, for young children or students with weak comprehension, we suggest that you can start with nine beads and complete the one or two addition and subtraction learning in about half a year. Before entering the multiplication, division and mental arithmetic teaching, switch to 1, 4 abacus learning.

The nine abacus is simple and convenient. It is a very suitable tool for cultivating young children to know the number and quantity. At the same time, establishing the foundation of the image and the beads is very helpful to the foundation of mathematics. At present, there are a variety of nine-bead abacus on the market, all using different colors to distinguish the upper and lower beads of the original 1,4-bead abacus. The top five are the top beads that represent 1, 4 beads, there is a color to represent, there is also a fifth to use a single color to emphasize that it belongs to the top bead, and the next bead is distinguished by another color. This has two advantages: when it is changed to 1, 4 abacus, it is easier to convert. Secondly, when learning mental arithmetic, the beads can be remembered by color, and there is no need to memorize five beads.

Therefore, some students are accustomed to learning nine beads and are unwilling to change back to 1, 4 beads is also feasible. Future courses, including mental arithmetic, multiplication and division, can be continued with nine beads. The purpose of learning abacus, if not for the pursuit of speed and advanced level, nine beads is also a good choice!