Math professor shows how adding and subtracting left to right is actually easier and faster
Mind. Blown.

Howie Hua shares helpful math tips and tricks on social media.
Math is weird.
On the one hand, it's consistent—the solutions to basic math problems are the same in every country in the world. On the other hand, there are multiple strategies to get to those solutions, and it seems like people are still coming up with new ones (much to the chagrin of parents whose kids need help with homework using methods they've never learned).
Math professor Howie Hua shares math strategies that make math easier on social media, and his videos are fascinating. Hua, who teaches math to future elementary school teachers at Fresno State, demonstrates all kinds of mental math tricks that feel like magic when you try them.
For instance, Hua has two videos showing how easy and quick it is to add multidigit numbers left to right instead of right to left, and it's genuinely mind-blowing.
Check out how he explains why adding left to right is "underrated."
\u201cNew TikTok video: Adding left to right is underrated\u201d— Howie Hua (@Howie Hua) 1665353677
OK, seriously. That is way easier to do in your head. It's basically putting the numbers into expanded form and adding them, which makes it easier to visualize.
Adding this way makes sense, but subtracting is a bit more complicated, right?
Wrong, apparently. Watch Hua work his math sorcery subtracting two and three-digit numbers.
@howie_hua Did you know you can subtract left to right? #math #mathematics #mathtok #maths #teachersoftiktok #teacher #mathtricks #mathtrick
Holy moly. That's faster than the right-to-left, borrow-from-the-next-column method, isn't it? And again, so much easier to visualize what's actually happening, though I don't know if I could fully do this in my head like I could with the left-to-right addition.
Hua recently shared another cool subtraction trick for problems with minuends that have a lot of zeroes. (The minuend is the first number in a subtraction problem. Don't be too impressed. I had to look it up.)
Check this out:
@howie_hua An underrated subtraction strategy #math #mathematics #mathtok #maths #teachersoftiktok #teacher #mathtricks #mathtrick
So simple, so time-saving and so something I would never have figured out on my own.
These tips and tricks might come in handy for anyone, but they're especially useful for kids who are having to do these kinds of math problems at school all the time. Even if they're supposed to solve the problem with a different strategy, these methods can be a quick way to check their answers.
Anything that makes math easier, I say. You can watch Hua's videos on TikTok, YouTube and Twitter.
This article originally appeared on 10.12.22
12 non-threatening leadership strategies for women
We mustn't hurt a man's feelings.
Men and the feels.
Note: This an excerpt is from Sarah Cooper's book, How to Be Successful Without Hurting Men's Feelings.
In this fast-paced business world, female leaders need to make sure they're not perceived as pushy, aggressive, or competent.
One way to do that is to alter your leadership style to account for the fragile male ego.
Should men accept powerful women and not feel threatened by them? Yes. Is that asking too much?
IS IT?
Sorry, I didn't mean to get aggressive there. Anyhoo, here are twelve non-threatening leadership strategies for women.
Encourage.
With permission from Sarah Cooper.
When setting a deadline, ask your coworker what he thinks of doing something, instead of just asking him to get it done. This makes him feel less like you're telling him what to do and more like you care about his opinions.
Sharing ideas.
With permission from Sarah Cooper.
When sharing your ideas, overconfidence is a killer. You don't want your male coworkers to think you're getting all uppity. Instead, downplay your ideas as just "thinking out loud," "throwing something out there," or sharing something "dumb," "random," or "crazy."
Email requests.
With permission from Sarah Cooper.
Pepper your emails with exclamation marks and emojis so you don't come across as too clear or direct. Your lack of efficient communication will make you seem more approachable.
Idea sharing.
With permission from Sarah Cooper.
If a male coworker steals your idea in a meeting, thank him for it. Give him kudos for how he explained your idea so clearly. And let's face it, no one might've ever heard it if he hadn't repeated it.
Sexism.
With permission from Sarah Cooper.
When you hear a sexist comment, the awkward laugh is key. Practice your awkward laugh at home, with your friends and family, and in the mirror. Make sure you sound truly delighted even as your soul is dying inside.
Mansplain.
With permission from Sarah Cooper.
Men love explaining things. But when he's explaining something and you already know that, it might be tempting to say, "I already know that." Instead, have him explain it to you over and over again. It will make him feel useful and will give you some time to think about how to avoid him in the future.
Mistakes.
With permission from Sarah Cooper.
Pointing out a mistake is always risky so it's important to always apologize for noticing the mistake and then make sure that no one thinks you're too sure about it. People will appreciate your "hey what do I know?!" sensibilities.
Promotions.
With permission from Sarah Cooper.
Asking your manager for a promotion could make you seem power- hungry, opportunistic, and transparent. Instead, ask a male coworker to vouch for you. Have your coworker tell your manager you'd be great for the role even though you don't really want it. This will make you more likely to actually get that promotion.
Rude.
With permission from Sarah Cooper.
Sometimes not everyone is properly introduced at the start of a meeting. Don't take it personally even if it happens to you all the time, and certainly don't stop the meeting from moving forward to introduce yourself. Sending a quick note afterward is the best way to introduce yourself without seeming too self-important.
Interruptions.
With permission from Sarah Cooper.
When you get interrupted, you might be tempted to just continue talking or even ask if you can finish what you were saying. This is treacherous territory. Instead, simply stop talking. The path of least resistance is silence.
Collaboration.
With permission from Sarah Cooper.
When collaborating with a man, type using only one finger. Skill and speed are very off-putting.
Disagreements.
With permission from Sarah Cooper.
When all else fails, wear a mustache so everyone sees you as more man-like. This will cancel out any need to change your leadership style. In fact, you may even get a quick promotion!
In conclusion...
With permission from Sarah Cooper.
Many women have discovered the secret power of non-threatening leadership. We call it a "secret power" because no one else actually knows about it. We keep our power hidden within ourselves so that it doesn't frighten and intimidate others. That's what makes us the true unsung heroes of the corporate world.
About the Author: Sarah Cooper
Sarah Cooper is a writer, comedian, and author of 100 Tricks to Appear Smart in Meetings. Her new book, How to Be Successful Without Hurting Men's Feelings, is out now.
The comedic book cover.
With permission from Sarah Cooper.
A satirical take on what it's like to be a woman in the workplace, Cooper draws from her experience as a former executive in the world of tech (she's a former Googler and Yahooer). You can get the book here.
This article was originally published on March 25, 2019.