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Several mathematics problems in grade one of junior high school~ In a certain month, Mr. Wang will participate in three days of business training. The sum of the numbers of the three days is 39. If the training time is three consecutive days, then the three days are respectively the 12th, 13th and 14th. If the training time is three consecutive weeks of Saturday, what are the dates of the month, the 13th and the 14th? According to the regular arrangement of a column of numbers: 2, - 4,8, - 16,32, - 64,..., in which the sum of some four adjacent numbers is - 640, how much is the difference between the maximum number and the minimum number of these four numbers? [Note: the solution of column equation is urgent!]
Let the intermediate days be X
Lie De equation X-7 + X + X + 7 = 39
3X=39
X=13
13-7=6 13+7=20
6, 13, 20
128,-256,512,-1024
The difference is 512 - (- 1024) = 1536
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