15500 in standard form

I would call that standard form! If you mean scientific form it is 1.55*10^4

Ok, an internet search suggests that standard form is another way of saying scientific form!

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I am amazed Alan !

I was always taught that the world at large would say

$$1.55*10^4$$      is in Scientific Notation.

BUT the English would say it was in   Standard Form

This was an irritation to me at school because the two terms were used interchangably and like you I thought an ordinary number should be in standard form.

Now you are English and you say you do not know the term Standard Form !! I am amazed !!