Fill in the appropriate sign to make the equation hold: 1 2 3 4 5 6 7 8 9 = 1000

Fill in the appropriate sign to make the equation hold: 1 2 3 4 5 6 7 8 9 = 1000

〔1－2＋3〕×4× 5×〔6×7－8－9〕=1000

Fill in the brackets with the appropriate notation
① 2 / 5 () 1 / 2 = 1 / 5 ② 5 / 8 () 5 = 1 / 8 ③ 1 / 4 () 2 / 3 = 11 / 12
④ 2 of 9 () 1 of 9 = 2 ⑤ 1 of 3 () 1 of 6 = 1 of 6 ⑥ 1 () 13 of 11 = 11 of 13
Fast

① 2 / 5 (×) 1 / 2 = 1 / 5
② 5 out of 8 (?) 5 = 1 out of 8
③ 1 / 4 (+) 2 / 3 = 11 / 12
④ 2 / 9 (?) 1 / 9 = 2
⑤ 1 / 3 (-) 1 / 6 = 1 / 6
⑥ 13 out of 11 = 11 out of 13
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Divide 1,2,3,4,... 19992000 numbers into five groups. If the average of each group is exactly equal, what is the sum of these five average numbers?
Details to explain, the method. Formula all written out!

5002.5 a total of two thousand numbers, divided into five groups on average, each group is 400 numbers, the average of the 400 numbers should be (2000 + 1) / 2 = 1000.5, so the sum of the average of the five groups is 1000.5 * 5 = 5002.5, just like: 1 23 4 5 6 7 8 9 10 divided into five groups, the first group is: 1 and 10, the second group is: 2 and 9, the third group is