"I'll try if I know all the things I used to know" is a quote from Lewis Carroll's works, reflecting a sense of nostalgia or difficulty in recalling previous knowledge. The quote humorously illustrates the struggle with memory as the speaker attempts to recite multiplication tables, but makes errors, such as claiming four times five is twelve instead of twenty, and four times six is thirteen instead of twenty-four. This highlights the playful and whimsical tone of Carroll's writing.

Through these humorous mistakes, Carroll captures a child's perspective on learning and the confusion that can come with trying to remember facts. It also hints at the theme of the book—wonder, curiosity, and the odd, sometimes nonsensical, nature of children's understanding of the world. The quote exemplifies the charming, humorous style that makes Alice's adventures both entertaining and thought-provoking.