Remove 1.3 from 13 strings

[Gambitboy]

This reverts commit c361820.

This PR is to revert the use of 1.3 as a string.
The proof provided for its case was incorrect and thus should be removed.
#420

First to disproof the proof

13 x 0 = 1.3 x 0
This is true because both sides equal 0

13 x 0 / 0 = 1.3 x 0 / 0
This point is not correct. The mistake made here is trying to divide by zero.
In mathematics dividing by zero is undefined thus this step is invalid.

This means:
1.3 != 13

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Second a proof for why 1.3 != 13

Lets assume this is correct:
1.3 = 13.
To clear the decimal we'll multiply both sides by 10.

1.3 x 10 = 13 x 10.
13 = 130.

This clearly is a contradiction, as 13 != 130

Thus, we can safely say.
1.3 != 13