I. Calculation
1、20 1 1-900+2009-902+2007-904+? ......？ + 1999-9 12=?
2、 1044*20 13+ 1046*20 1 1+ 1048*2009=?
What is the remainder of a =12345 * 54321+2468 * 8642a/7?
4. Remove one number at a time from the four numbers A, B, C and D, and then calculate the average. These four averages are 50, 38, 52 and 46 respectively. What's the biggest number?
5、20 1 1/A=()/ 13？ What are the eligible figures?
6.528 people went to the suburbs to plant trees? The plan * * * has a total of 1 167 trees, with each teacher planting 5 trees and each student planting 2 trees. In fact, each teacher will plant one less tree and each student will plant 1 tree. How many trees have actually been planted?
7, 1, 1, 2, 1, 2, 3,2, 1, 2, 3, 4, 3, 2, 1 ...
8、
10, put 23 identical parts in 5 identical boxes, ask someone to collect any number of parts between 1 and 23, and you can take them away without unpacking. How many ways are there?
1 1, and Li Chengbao contracted a project. Zhang and Wang cooperated for 5 days to complete 1/3 of the whole project, and Zhang and Li cooperated for 2 days to complete 1/4 of the remaining projects. Finally, Wang and Li cooperated for 5 days to complete the remaining projects. If the contract amount of the whole project is 4200 yuan, how much will Lao Zhang get? Divide money according to the total amount of work?
12, three cars, A, B and C, set off from a certain place at the same time and chased a cyclist along the same highway. One of the three cars caught up with the man in 6 minutes, 10 minutes and 12 minutes respectively. If car A travels at 1600 meters per minute and car B travels at 1200 meters per minute, ask car C.