Conversione dell'ora da Abū Qurqāş a Half Way Tree
18:31:12
-7
11:31:12
+7
+7
+7
+7
+7
+6
+6
+6
+6
+6
+6
+6
+6
+6
+6
+6
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+5
+5
+5
+4.5
+4
+4
+4
+4
+3.5
+3.5
+3.5
+3.5
+3.5
+3.5
+3.5
+3.5
+3.5
+3.5
+3
+3
+2.5
+2
+1.5
+1
+1
+1
+1
+1
+1
+1
+0
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-1
-1
-1
-1
-1
-1
-1
-2
-2
-5
-5
-5
-5
-6
-7
-7
-7
-8
-10