Math expert, come on! thank you

1. First number 645 copies, then select 8 copies by simple random sampling, then number the remaining 637 copies, then select a number n from the first 49 numbers, and then select N+49, N+98, N+ 147, N+ 196 until N. Then take 20 samples by simple random sampling, then number the remaining 480 samples, then take a number n from the first six numbers, and then take N+6, N+ 12, N+ 18, N+24 until N+472 * * 80 samples. The first is 40 students. 02。 03. From 0 to 40, when looking up the random number table, start with two numbers in any row and any column of the random number table. If it is from 0 1 to 40, it means it is not there. If it's 83, don't get eight numbers. This is a random number method, which is suitable for students who have drawn the same number.