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."
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
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An Irish woman went to the doctor for a routine eye exam. She left with bright neon green eyes.
It's not easy seeing green.
Did she get superpowers?
Going to the eye doctor can be a hassle and a pain. It's not just the routine issues and inconveniences that come along when making a doctor appointment, but sometimes the various devices being used to check your eyes' health feel invasive and uncomfortable. But at least at the end of the appointment, most of us don't look like we're turning into The Incredible Hulk. That wasn't the case for one Irish woman.
Photographer Margerita B. Wargola was just going in for a routine eye exam at the hospital but ended up leaving with her eyes a shocking, bright neon green.
At the doctor's office, the nurse practitioner was prepping Wargola for a test with a machine that Wargola had experienced before. Before the test started, Wargola presumed the nurse had dropped some saline into her eyes, as they were feeling dry. After she blinked, everything went yellow.
Wargola and the nurse initially panicked. Neither knew what was going on as Wargola suddenly had yellow vision and radioactive-looking green eyes. After the initial shock, both realized the issue: the nurse forgot to ask Wargola to remove her contact lenses before putting contrast drops in her eyes for the exam. Wargola and the nurse quickly removed the lenses from her eyes and washed them thoroughly with saline. Fortunately, Wargola's eyes were unharmed. Unfortunately, her contacts were permanently stained and she didn't bring a spare pair.
- YouTube youtube.com
Since she has poor vision, Wargola was forced to drive herself home after the eye exam wearing the neon-green contact lenses that make her look like a member of the Green Lantern Corps. She couldn't help but laugh at her predicament and recorded a video explaining it all on social media. Since then, her video has sparked a couple Reddit threads and collected a bunch of comments on Instagram:
“But the REAL question is: do you now have X-Ray vision?”
“You can just say you're a superhero.”
“I would make a few stops on the way home just to freak some people out!”
“I would have lived it up! Grab a coffee, do grocery shopping, walk around a shopping center.”
“This one would pair well with that girl who ate something with turmeric with her invisalign on and walked around Paris smiling at people with seemingly BRIGHT YELLOW TEETH.”
“I would save those for fancy special occasions! WOW!”
“Every time I'd stop I'd turn slowly and stare at the person in the car next to me.”
“Keep them. Tell people what to do. They’ll do your bidding.”
In a follow-up Instagram video, Wargola showed her followers that she was safe at home with normal eyes, showing that the damaged contact lenses were so stained that they turned the saline solution in her contacts case into a bright Gatorade yellow. She wasn't mad at the nurse and, in fact, plans on keeping the lenses to wear on St. Patrick's Day or some other special occasion.
While no harm was done and a good laugh was had, it's still best for doctors, nurses, and patients alike to double-check and ask or tell if contact lenses are being worn before each eye test. If not, there might be more than ultra-green eyes to worry about.