(I work as a chemist. I’m fairly new, and one of the youngest people working. An internal customer comes in, wanting help interpreting the data I sent him. Note: this man has a PhD in chemistry.)

Customer: “I need this in percent! You sent it in… ppm?? What is that?!”

Me: “It stands for part per million.”

Customer: “Well, how do I get percent?

Me: “You have to convert to part per hundred. It’s just an order of magnitude conversion.”

Customer: “Part per hundred isn’t what I need, either! I need percent!”

Me: “Part per hundred is percent. That’s what percent literally means. Per hundred.”

Customer: “No, it doesn’t!”

(Repeat for ten minutes. I eventually gave up and did the conversion for him. Makes me wonder what math classes he took in that PhD.)

(I am a handyman and almost always work alone, but I am working on a bigger project and could use some assistance. As I am leaving [Home Improvement Store], a young man comes up to me.)

Young Man: “Hey, man, need some help? I need a job real bad.”

(The baggy clothes, cigarette hanging from his lip, and dirty appearance turn me off, but I am willing to perhaps see if he might have some skills I can use.)

Me: “How are your math skills?”

Young Man: *proudly* “I don’t need no stinkin’ math; I’m gonna be a carpenter!”

(I assured him that I did not need his help.)

(A customer comes in with a coupon we are running that allows them to buy six bagels and get six free. We have some specialty bagels that are not covered under the coupon and add 55 cents more a piece to the final total.)

Customer: “Hi, I’d like to do this deal.” *shows me the coupon*

Me: “Great. Have you been here before, and do you know that the specialty bagels are 55 cents more?”

Customer: “55 cents? No problem.”

(The customer picks ten specialty bagels and two regular bagels. If he had picked all regular bagels the total would have been $6.60.)

Me: “All right, your total is $11.50.”

Customer: “What?! I thought it would be like $7.”

Me: “Well, yeah, but you got ten specialty bagels and I explained that there was a cost increase.”

Customer: “$7 plus 55 cents does not equal more than $11!”

Me: “I’m sorry, sir, maybe I didn’t explain it properly; they are 55 cents more each.”

Customer: “I thought it was just a one-time fee of 55 cents.”

(Sadly, one of the owners was there and told me to charge the specialty bagels at the regular price so it was $6.60. The same customer has pretended to misunderstand that explanation several times now and I have learned my lesson to say that the upcharge is for each bagel, not a one-time fee.)

(I go to a home improvement store as I need a ⅝-inch drill bit. I look at the display, and the largest I see is a ½-inch. I finally find three young employees talking to each other. I interrupt, asking for help. One looks at me with disgust that I have interrupted their football discussion.)

Employee: “Whaddya want?”

Me: “I’m looking for a ⅝-inch drill bit.”

Employee: “They’re over there.” *generally pointing*

Me: “I looked over there and the largest I saw was a 1⁄2-inch.”

Employee: *loud sigh* “Okay.”

(He takes me back to the display rack and starts looking at the tiny drill bits.)

Me: “Not the little ones; ⅝-is bigger than 1⁄2, and 1⁄2 seems to be the largest I can find.”

Employee: “NO, IT’S NOT! I learned in school that if the big number is on the bottom that makes the fraction real little!”

Me: “…”

(I have neither the time nor the patience to educate stupidity.)

(It’s no secret in my family that I’m very good at mental arithmetic. As a result, I’m frequently used to calculate any number of things going on in their lives under the pretense of “save me from finding the calculator.” Usually, it’s just a minor inconvenience in my day. Then, my dad says the magic words.)

Dad: “So, it measures 7 feet, by 7 feet, by 4 inches. How many cubic feet is that?”

Me: “16 1/3.”

Dad: “No! That’s too small!”

Me: “You said 7 feet, by 7 feet, by 4 inches, right?”

Dad: “Right.”

Me: “And there’s 12 inches to a foot, right?”

Dad: “Right.”

Me: “So, 4 inches is equal to 1/3 of a foot, right?”

Dad: “Right.”

Me: “So, 7, times 7, times 1/3. That’s 16 1/3.”

Dad: “No! You have to convert it to cubic inches first!”

Me: “Really?! You’re making me do it that way?”

Dad: “Yes, that’s how you do it.”

(Groaning and shaking my head, I do this considerably longer calculation.)

Me: “That’s 28,224 cubic inches, so… 16 1/3 cubic feet. Again.”

Dad: “What?! How did you turn 28,000 into 16?!”

(I grab a pencil and paper and walk him through every step of my work. We arrive at 28,224 just fine, and then we get to converting.)

Me: “So now we divide by 1728.”

Dad: “No! There are only 12 inches to a foot!”

Me: “It’s a CUBIC foot, Dad. That’s a cube measuring 12 inches, by 12 inches, by 12 inches. That’s 1728 cubic inches to the cubic foot. Or are you going to tell me that you think the answer is 2352 cubic feet?”

Dad: “You did something wrong!”

(He storms off, right towards the calculator. Meanwhile, I’ve pulled out my phone and found a source that proves there are 1728 cubic inches to a cubic foot, just in case I still need it, which I do. By the end of this encore of a needless conversion, we have, once again, arrived at 16 1/3.)

Dad: “THAT CAN’T BE RIGHT!”

Me: “Why don’t you show me what I’m calculating?”

(He leads me to the backyard and shows me a big, rectangular hole.)

Dad: “This is for the shed. I dug it out, and I just need to smooth it out. Tomorrow, I’m going to fill it. I need to know if I’ve got enough bags of cement. If it’s 16 1/3, I’d only need one bag, but I’m definitely going to need more like 30.”

(I see one of the bags he has out, and I start reading it to make sure all of his numbers are right. The bag says it’s good for 20 cubic feet of concrete, so by all outward appearances, my math is sound. Then, as I ponder why my dad insists he’s going to need 30, the gears in my head start winding.)

Me: “Dad, you are going to use concrete, right?”

Dad: “Yes!”

Me: *realizing how poorly I phrased my previous question* “Walk me through it. You empty this bag into the… whatever, and then?”

Dad: “Then I add the water until it’s the right consistency.”

Me: “That’s it?”

Dad: “Well, then I pour it, smooth it out, and build the shed.”

Me: *facepalming* “Oh, my God.”

Dad: “What?”

Me: “You don’t know the difference between cement and concrete, and you’ve done work on this house.”

(At least now we knew what the problem was. Now to figure out how many of his fixes around the house have to be redone.)