What does $^3 3$ mean?

I was taking a test and this was a question. It does not mean $3^3$, nor is it a typo. The superscript was before the $3$ and I have no idea what it means. I tried researching but couldn't find an answer. The answer was $10^{13}$ when rounding if that helps anyone.

This notation is sometimes used for tetration. And in fact $$3^{3^3} \approx 7.6 \times 10^{12}$$ so not that far from $10^{13}$.