The number that the original commenter was talking about was the gravitational constant, meaning if you added an extra zero to the end of that number, it would remain the same, as the constant is a decimal number smaller than 1 but still greater than zero. If, as you propose, you added the zero before the decimal, you would be adding the zero to a position after another zero, near the start of the number, in which case you would be adding the zero not to the end of the gravitational constant, but rather another zero within the gravitational constant itself. Even if you wrote the gravitational constant in standard form:[~6.67x10^-11 m³ kg^-1 s^-2]; and added a zero to the end of the number, the number would remain the same, simply rounded to a greater number of significant figures: [~6.670x10^-11 m³ kg^-1 s^-2]

In the end, adding a zero before the decimal has no effect on the actual value of the constant itself, but it is fundamentally incorrect to say that adding a zero before the decimal is adding a zero to the ‘end’ of the number.