This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Even if you use rote memorization to memorize them in the short term, you'll forget them again quickly, won't you?
How many digits of pi can you remember, Sakuragi?
He's the class clown and is always playing the fool, but he is very good at memorization.