mathematics and astronomy

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6:07

11:50

12:12

10:05

5:24

15:11

19:08

00:55

9:03

5:11

1:13:59

42:36

10:25

9:21

31:12

5:29

15:48

3:32:45

3:53

1:23:14

1:38:28

1:05:37

3:09

6:23

6:23

14:12

28:03

2:15:22

11:25

15:47

40:01

9:41

1:41:15

17:04

10:01

4:43

46:40

10:10

10:46

1:50:41

10:50

4:19

2:07:48

48:26

1:02

1:44

00:43

23:07

1:14:05

11:41

7:43

1:56:19

42:27

16:59

1:34:09

1:36

48:58

4:08

11:53