With the method of abacus calculation, it is easy to work out: 1+ 1=2. In binary, 1+ 1= 10. Add and subtract with abacus, which is more intuitive. Its basic principle is the arrangement of numbers, counting from high places.

The basic principle is decimal notation, with a bead at the end of five and a forward bead at the end of ten. Add by beam and subtract by frame.

First, direct addition.

When dialing the addend, dial the beads directly at the light beam.

One up one, two up two, three up three, four up four, five up five, six up six, seven up seven, eight up eight, nine up nine.

Second, full five addition.

If the addend is less than 5, it is a number less than 5. You need to add five and subtract the extra number.

One five divided by four, two five divided by three, three five divided by two, and four five divided by one.

Third, carry addition. The same gear, the sum of two numbers is ten, and one is advanced.

One divided by nine gets one, two divided by eight gets one, three divided by seven gets one, four divided by six gets one, five divided by five gets one, six divided by four gets one, seven divided by three gets one, eight divided by two gets one, and nine divided by one gets one.

Fourth, break the five-digit addition. This file already has beads on the top beam, so you should add up the numbers 6, 7, 8 and 9 and subtract one. If the beads are not enough, add five points first, and then advance one. Six plus one divides five into one, seven plus two divides five into one, eight plus three divides five into one, and nine plus four divides five into one.

I hope it can help you solve the problem.