You might remember the meaning of the character 合 with this easy mnemonic:
Through word of <strong>mouth</strong> (口), you heard about this <strong>one</strong> (一) really cool book. You don't know what it's about, but both <strong>men</strong> (人) and women want to read it. This includes you too. You finally got your hand on it. It's impossible <strong>to close</strong> and put it down. You finished reading it in one sitting.
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.