5eo+5eo
5e0 (note zero not lower case letter o) usually means 5*10^0 which is just 5, so 5e0 + 5e0 is 10.
Using e0 (or E0) to represent *10^0 is a legacy of text-only input to some computer languages.
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$$\left(\mathrm{ERROR}\right)\,{ and }\,\left({\mathtt{0.09}}{\mathtt{\,\times\,}}{\mathtt{related}}\right)$$
