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← Mathematics: stupid and clever questions for people who understand

epeeist's Avatar Jump to comment 51 by epeeist

Comment 50 by Teknical :

If 'infinity' is a number and 1, 3, 5, 7, is half an infinity because half of the numbers are missing and I imagine it would be expressed as 'infinity' divided by 2.

If you write all the cardinal numbers down in a row and then the odd numbers underneath, like so:

1 2 3 4 5...

1 3 5 7 9...

You can see that you can match each of the numbers on the second row to one on the first row, thus the two have the same cardinality, i.e. aleph zero

Sat, 02 Jun 2012 10:10:18 UTC | #945172