5th january 2009
numeracy
1 x 1 1 + 1
and and
1 ¸ Ö 1 - ½
october 2009
permutations combinations
there are two permutations of 1 and 2... there is one combination of 1 and 2...
1/2 and 2/1 1/2
1 x 2 = 2 1 + 1 = 2 - 1 = 1
there are six permutations of 1, 2 and 3... there are three combinations of 1, 2, and 3...
1/2/3, 1/3/2, 2/1/3, 2/3/1, 3/1/2 and 3/2/1 1/2, 1/3 and 2/3
1 x 2 x 3 = 6 1 + 2 + 3 = 6 - 3 = 3
there are twenty four permutations of 1, 2, 3 and 4... there are six combinations of 1, 2, 3, and 4...
1/2/3/4, 1/2/4/3, 1/3/2/4, 1/3/4/2, 1/4/3/2, 1/4/2/1, 1/2, 1/3, 1/4, 2/3, 2/4, and 3/4
2/1/3/4, 2/1/4/3, 2/3/1/4, 2/3/4/1, 2/4/1/2, 2/4/1/3, 1 + 2 + 3 + 4 = 10 - 4 = 6
3/1/2/4, 3/1/4/2, 3/2/1/4, 3/2/4/2, 3/4/1/2, 3/4/2/1, there are ten combinations of 1, 2, 3, 4, and 5..
4/1/2/3, 4/1/3/2, 4/2/1/3, 4/2/3/1, 4/3/1/2 and 4/3/2/1 1/2, 1/3, 1/4, 1/5, 2/3, 2/4, 2/5, 3/4, 3/5, and 4/5
1 x 2 x 3 x 4 = 24 1 + 2 + 3 + 4 + 5 = 15 - 5 = 10
and so on and so on
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