Number theory in grade six of primary school The 999 numbers of 1234... 999 are evenly arranged in a big circle, counting from 1: cross out 23 every 1, cross out 56 every 4... So cross out two numbers every other number, and circle them. Question: which number is left? Why? Process

Number theory in grade six of primary school The 999 numbers of 1234... 999 are evenly arranged in a big circle, counting from 1: cross out 23 every 1, cross out 56 every 4... So cross out two numbers every other number, and circle them. Question: which number is left? Why? Process

There are three numbers in a cycle. 999 △ 3 = 333333 △ 3 = 111 111 △ 3 = 37 1 is always the first number. After three cycles, the rest is 12855.973, a total of 37 numbers. In the fourth cycle, the rest is 182163.892973 (the first number). In the fifth cycle, the rest is 163406649892 (the next one is