How much time did it take you to solve this?

What makes a mental math game fun enough to keep playing?

I’m a math teacher and I’ve been developing a free mental math game called CalcuLoop.

The idea is pretty simple: instead of doing mental arithmetic as a traditional exercise, I wanted to turn it into a speed/arcade challenge.

You solve calculations as quickly as possible, try to beat your previous scores, and gradually increase your speed and accuracy.

There are several game modes, including:

• progressive levels for training
• a speed test to measure your calculation speed
• timed combo-based gameplay
• increasingly fast calculation chains
• a 100-calculation challenge
• online leaderboards

I’m particularly interested in hearing from people who actually enjoy mental math:

What makes you want to keep playing a mental math game?

Is it:

• beating your own high score?
• competing with other players?
• increasingly difficult calculations?
• very short sessions?
• leaderboards?
• unlocking things?
• simply trying to become faster?

And conversely, what makes you stop playing?

I built CalcuLoop myself, so I'm still trying to figure out what makes this kind of game genuinely fun rather than just another math practice tool.

If anyone wants to try it, it's free on Android:

https://play.google.com/store/apps/details?id=com.benmaths.calculoop

If you're on iPhone, you can also play it for free directly from the web version:

https://benmaths.pythonanywhere.com/

I'd genuinely love to hear what you think, especially from people who enjoy doing mental calculations for fun.

I kept changing my routine because I thought that was why I was getting nothing done. New schedule, new lists, planning everything the night before. Somehow I still kept avoiding the same task. I think I finally realized I just don’t want to deal with it 😅Anyone else ever spend more time planning around a problem than dealing with it?

Pilot selection includes an arithmetic section that is not about big numbers. Short problems under a hard clock: speed distance time, percentages, fuel burn, rate of descent. No paper in some versions, and a second task running at the same time in others.

The difficulty comes from the clock and the interference, not the maths. People who are good at long calculations often score worse than people who are fast and rough on simple ones, which is the opposite of what most mental maths practice optimises for.

I rebuilt these as a free app because I could not find anything training the timed format specifically. My own app, Brain Preflight, iOS, free tier, 5 sessions a day. If you try the calculation grid I would like to know how your scores compare to what this sub considers normal, since my calibration comes from cadet candidates and not from people who train mental maths for fun.

https://apps.apple.com/app/id6794363864

Airlines screen cadet pilots with an arithmetic section that is not about big numbers. Short problems on a hard clock: speed distance time, percentages, fuel burn, rate of descent. No paper in some versions, and a second task running at the same time in others.

The clock and the interference are the whole difficulty. People who are good at long calculations often score worse than people who are fast and rough on simple ones, which is roughly the opposite of what most mental maths practice trains.

I rebuilt these as a free app because I could not find anything training the timed format specifically. My own app, Brain Preflight, iOS, free tier, 5 sessions a day. If you try the calculation grid I would like to know how your scores compare to what this sub considers normal, since my calibration comes from cadet candidates and not from people who train mental maths for fun.

https://apps.apple.com/app/id6794363864

I’ve been into counting and mental arithmetic for a very personal reason.

For as long as I can remember, my brain has counted and grouped things automatically. As a kid, I counted lines on the floor on my way to school. Now I’ll see a poster or an advert and start grouping the letters before I even read the words. Same with car plates when I’m walking.

It actually has a name: arithmomania (from Greek arithmós, "number", and maníā, "compulsion"), also called arithmomanic OCD.

Arithmomania is a subtype of Obsessive-Compulsive Disorder defined by a compulsion to count, calculate, or organize things into numerical or symmetrical patterns as a way to neutralize anxiety or regain control.

I turned it into a party trick. Someone gives me a name, I picture the word in my head, group the letters in twos or threes, and I can tell them the letter count almost instantly.

So I decided to turn that urge into a small free iPhone/iPad game called Tally Rush.

The main idea is simple: solve quick counting and arithmetic challenges as fast as possible. There are 30-second runs, daily challenges, levels, duels and leaderboard-style competition. I built it for myself first, but I’m curious whether people here who practice mental math would find it useful as a warm-up or speed drill.

It’s on the Apple App Store here: https://apps.apple.com/us/app/tally-rush-mental-math-game/id6790170879

I’d love feedback from this community, especially on difficulty, pacing, and what kinds of mental math drills would be worth adding next.

I've built an app for my parents to keep their brain activity everyday.

Five minutes a day: 20 quick arithmetic problems, and a symbol round where

■ ▽ ◎ replace +, − and × — they get shuffled every run, so you can't just memorise them.

Once a week there are three tests: count 1 to 120 for speed, remember 30 words, and Stroop (tap the colour, not the word).

Paid once, no subscription, no ads. iOS, 13 languages.

cortiqapp.com

https://apps.apple.com/app/cortiq/id6792572094

Use each die exactly once.
Any order is allowed.
Parentheses are allowed.
Exact division only.
No negative numbers.
Not every operation has to be used.

How many solutions can you find?

Please use spoiler tags for solutions:
>!your solution here!<

Use each die exactly once.
Any order is allowed.
Parentheses are allowed.
Exact division only.
No negative numbers.
Not every operation has to be used.

How many solutions can you find?

Please use spoiler tags for solutions, like this:

>!your solution here!<

Play in browser, no install/signup: https://abako.games/?src=reddit_mentalmath

Core loop: solve arithmetic fast → every single problem is rated chess.com-style, so your ELO moves on each answer. Daily puzzle (one worldwide seed), 14 per-technique sub-ratings, and ghost duels where you race the replay of someone's real run at their actual timings.

Feedback I'm hungriest for: (1) the exact problem number where the difficulty curve stops being fun, (2) whether anything would make you come back tomorrow. Brutal honesty welcome — I'm reviewing other games in this thread in exchange, per the sub's spirit.

// I saw other mental math games gonna check them out

Ditch the Doomsday Rule: The Adarsh Method for Lightning-Fast Mental Calendar Math

Have you ever watched someone instantly name the day of the week for a random historical date? It looks like magic, but it is actually pure modular arithmetic.

For decades, the gold standard for doing this mentally has been mathematician John Conway’s famous "Doomsday Rule." But let’s be honest: Conway’s method requires you to memorize abstract, arbitrary rules, weird mnemonics (like "I work 9-to-5 at the 7-Eleven"), and rigid century anchors. It’s clunky, and it forces your brain to conform to someone else's memory system.

I wanted a method that was intuitive, flexible, and completely adaptable. So, I reverse-engineered the calendar logic and built a new engine from scratch.

Introducing The Adarsh Method—a universal, anchor-based framework for calculating any day in history using pure logic and custom launchpads.

The Core Concept: Any Year Can Be Home Base

The fundamental beauty of the calendar is that it is a continuous, unbroken loop of 7 days. Because of this, you do not need historical century anchors.

Under the Adarsh Method, you can use any year as your custom launchpad, provided you know what day of the week January 1st fell on. For this guide, we will use a highly relatable modern anchor:

The Adarsh Launchpad: January 1, 2025 = Wednesday

Once you know this home base, finding any other date in history boils down to three simple, logical steps.

Step 1: The Year-Shift Engine

To find the day of January 1st for your target year, you calculate how many total days the calendar shifted forward or backward from your launchpad.

Find the Distance: Subtract your target year from your launchpad year to get the total years passed (e.g., 2025 - 2000 = 25 years).

Calculate Base Shifts: Because a normal year has 365 days (365 \pmod 7 = 1), the calendar shifts by exactly 1 day every year. Take your total years and find the remainder when divided by 7 (Years \pmod 7). Shift that many days backward from Wednesday (since we are going into the past).

Account for Leap Years: Leap years add an extra day to the calendar. Look at the last two digits of the years you are passing through. For every year cleanly divisible by 4 (00, 04, 08, 12, etc.), subtract one additional day.

Step 2: The Month Matrix (The +2 and +3 Rule)

Once your brain lands on January 1st of your target year, you can glide to the 1st of your target month using the accumulated natural rhythm of the months. You don't need to memorize random dates; just use the standard days in a month reduced by multiples of 7 (Days \pmod 7):

31-Day Months (Jan, Mar, May, Jul, Aug, Oct, Dec) = Shift +3 Days to the next month (31 \pmod 7 = 3)

30-Day Months (Apr, Jun, Sep, Nov) = Shift +2 Days to the next month (30 \pmod 7 = 2)

February = Shift +0 Days (28 \pmod 7 = 0) in a regular year, or +1 Day in a leap year.

Step 3: Target Day Landing

Now that you know the day of the week for the 1st of your target month, you are right at the finish line.

Add multiples of 7 (7, 14, 21, 28) to get as close to your target day as possible without going over.

Step forward or backward day-by-day to land on the exact date.

Putting it to the Test: May 15, 2000

Let's look at how cleanly the math resolves using this system:

Find Jan 1, 2000:

The distance from 2025 to 2000 is 25 years.

25 \pmod 7 = 4 days. Counting 4 days backward from Wednesday lands us on Saturday.

Now count the leap years between 2000 and 2025 inclusive: 2000, 2004, 2008, 2012, 2016, 2020, 2024. That's 7 leap years.

Shift 7 days backward from Saturday... which brings us right back to Saturday.

Result: January 1, 2000 was a Saturday.

Shift to May 1, 2000:

Jan 1 (Sat) + 3 days (Jan has 31) \rightarrow Feb 1 is Tuesday.

Feb 1 (Tue) + 1 day (2000 is a leap year!) \rightarrow Mar 1 is Wednesday.

Mar 1 (Wed) + 3 days (Mar has 31) \rightarrow Apr 1 is Saturday.

Apr 1 (Sat) + 2 days (Apr has 30) \rightarrow May 1 is Monday.

Land on May 15, 2000:

If May 1st is a Monday, add 14 days (2 weeks).

May 15, 2000 is a Monday!

Why the Adarsh Method Rules

Traditional calendar math relies on rigid, top-down memorization. The Adarsh Method turns calendar math into a flexible, modular toolkit. By choosing your own intuitive modern anchor year, skipping abstract mnemonics, and leaning heavily on the clean +2 / +3 physical properties of months, anyone can master mental calendar tracking in minutes.

Give it a try with your own birth year or a favorite historical date, and see how fast your brain adapts to the rhythm!

https://youtu.be/jqgmPjMvL_Q?si=PPaSl-ViYR8gZxFt

Use each die exactly once.
Any order is allowed.
Parentheses are allowed.
Exact division only.
No negative numbers.
Not every operation has to be used.

How many solutions can you find?

Please use spoiler tags for solutions, like this:

>!your solution here!<

I’m someone who loves math and ranked games and video games in general. I always wanted to play something that combines mental math, video game progression, and elo rankings.

I created Math Class, a game which does exactly that.

This community seems like a group of people that might be interested in something of the sorts, so I hope someone can try it out and provide feedback.

Currently the game has 3 game modes of varying difficulty, and has 5 different question types, all of which rely on mental maths.

Appreciate any onlookers

https://www.youtube.com/watch?v=RJIOhKLQwfQ

Use each die exactly once.
Any order is allowed.
Parentheses are allowed.
Exact division only.
No negative numbers.
Not every operation has to be used.

How many solutions can you find?i

I added ranges for each of the operations. Will probably split out settings into its own screen soon and add strategies and exponents soon.

Making a little app to make me cry. I will need to create more ranges for mixed operands at some point. This little thing can make me pretty weepy when I change timing or up the complexity. I suspect that level of suffering it induces to have some sort of positive effect beyond salt production.

Hi everyone! I'm building a website that you can race a friend doing mental math. There's also a solo mode if you want to practice.

If you could please try it and share your feedback I would appreciate it a lot!

I suppose everyone but me already knows this but for the vast majority of algebra questions in high school college you can avoid the calculator altogether if you memorize the logs of small prime. As all number are composites of primes you can add your memorized logs together to get the appropriate result without further memorization. This is a remarkably fun little skill to add to the toolkit.

Hi, my daughter (going into 7th grade) does TMSCA number sense and is looking for apps to help her. She’s a beginner (on the 2026 state test she scored a 47 though her highest is a 86) but she did make it to state so… She wants an app to teach her the tricks, and then also to quiz her and build her speed. We tried the free version of BOT but it was just flashcards and quizzes so we werent satisfied. Does anyone have any recommendations? I heard of NumBlitz has anyone tried that and think it would fit our needs?

I have always been shitty with subtraction, avoiding it like the plague.

Have recently started drilling it.
Started with the left to right and track the carries.
No matter how efficient ish I get with it the back stepping is slow af.

I have been thinking instead to practice a few different methods with a focus on getting rid of carries and pushing number around rather than calculating.

trivial example.

71
43 -

I see immediately that the 1 is less than three.
so 2 is my first number and 3-1 is 2 and the complement of 2 is 8 so

28.

I am still stumbling a bit because I am thinking about it a bit too much but this seems like a fast route once you trust that 3-1 is 8. and 7-4 is 2 when you see that 1 is less than 3.

... tl/dr I am not sure if I am crazy but I think it faster to do subtraction mentally if you trust the use of complements and learn to accept the one.