Oh. Sorry about that. I have no idea how you're supposed to conjugate that. It's listed as archaic. I mean, it doesn't even make sense by modern Japanese standards. How could you conjugate a verb whose ending is also its kanji radical? Maybe you can't conjugate it actually. Maybe it only exists as う used in a specific expression (or several) and that's it. It wouldn't be a first in any language. French has a few verbs like that for instance.
Did you really find it listed on the N2 program? That can't be right.
In classical Japanese, at least, it works. It's just one of the weird 下二段 verbs like 寝 (ぬ
.
It gets confusing, because when you conjugate it...
(Made an example conjugation table that is accurate enough for the purposes I'm trying to get across. The ず、て、事、ば are not part of the verb conjugation and are only there to make it easier to understand.)
(未然形)得
ず (
えず) 「現代:得
ない」
(連用形)得
たり (
えたり)「現代:得
ました」
(終止形)得  (
う)   「現代:得る」
(連体形)得る
事 (
うる) 「現代:得る
事」
(已然形)得れ
ば (
うれ) 「現代:得る
ので」
(命令形)得よ  (
えよ) 「現代:得ろ」
...the kanji can represent different syllables depending on the 助動詞 that follow. Let's just say that it really makes you miss ichidan. Basically, in the first three, you simply get え/え/う if you only look at how the verb itself conjugates, which are represented by just the kanji itself. (In classical Japanese, things like conjunctions and negatives are their own helper verbs that follow certain forms--the 助動詞.)
So it is indeed "archaic", and I wouldn't worry about it in modern Japanese.
EDIT:
This probably explains it better than I did.