When I realized I needed 25 packs of beads to complete the miser's purse, I looked on the Mill Hill site and saw that they were $4.50 a pack.
Holy crap! Even I, clearly a math functional illiterate, know that 4 times 25 is 100. I didn't even bother figuring out 50 cents times 25, since I'd already hit 100.
I decided I wasn't worth it.
Then I thought I'd better check again. Turns out the pattern will need 25 packs that weigh 2.53 grams. For $4.50 I get 30 grams.
I decided to play it safe, not do any more math, and ordered 100 grams.
Christ on a cracker, this math stuff makes my head hurt.