[Tex/LaTex] getting an undefined control sequence error in this line?

Question

This question already has an answer here:

What library do I have to use such that the document can render \lt and \gt as less than and greater than signs, respectively?

(1 answer)

Closed 6 years ago.

This line is giving me an error which I have been unable to remove for the last hour.

Let $a^i =p\times 10^{n+1} + r$ and $a^j =q\times 10^{n+1} + r$
be two such powers. Let $a^j \gt a^i$.

Answer 1

Changing the \gt to > makes the code compile without error message.

Let $a^i =p\times 10^{n+1} + r$ and $a^j =q \times 10^{n+1} + r$ 
be two such powers. Let $a^j > a^i$.