Here is an example that happened a few days ago. I went to a printing shop to print my daily work lists. I planned to do 30 copies double sided. I handed the list, asking the staff to make 30 copies as I asked. She did it, charged me RM 12, as it was 20 cents per side. (0.20 x 60 (double sided)), according to her. Then I noticed the price, below 50 copies, 20 cents per side, above 50 copies, 10 cents per side. So, if I asked her to do 50 copies instead, she would have charged me (0.10 x 100 (double sided) ), which would be only RM 10, saving me RM 2.
Lesson here – make sure you know your numbers, so you can measure everything. I was only focused on the number of copies, not the eventual cost vs savings. I call this my RM 2 lesson.