MathTre vs 巧工 · 古代机械三维互动馆

Sharpen your mental math in just a few minutes a day. MathTre is a simple math workout for addition, subtraction, multiplication, division, and running sums. Open the app, tap start, and you're training. No clutter, no setup. Squeeze in a quick session on your commute, between tasks, or before bed. The more you practice, the faster and more accurate your mental math becomes. ■ PERFECT FOR YOU IF YOU WANT TO... ・Do quick math in your head at the checkout or when splitting the bill ・Make brain training a daily habit and keep your mind sharp ・Build speed for aptitude tests, entrance exams, or certifications with math sections ・Practice abacus-style mental arithmetic and running sums ・Give your kids a simple, distraction-free tool for arithmetic practice ・Race the clock and keep setting new personal bests ■ WHAT YOU CAN DO WITH MATHTRE [5 calculation modes] Addition, subtraction, multiplication, and division, plus Sums, where you add up a series of numbers one after another. From basic arithmetic drills to abacus-style running totals, it's all in one app. [Difficulty from 1 to 5 digits] Set anywhere from 1 to 5 digits, and choose the digits for each number separately (for example, 2-digit × 1-digit). Start with easy warm-ups and work your way up to big numbers that challenge even seasoned mental math fans. You can also choose the number of questions and, in Sums mode, how many numbers to add. [Fresh problems every time] Problems are randomly generated for every session, so there's no memorizing the answers. Every round is a true test of your calculation skills. [Track your time, see your progress] MathTre automatically records your clear time and your time per question. Beat your best and you'll see "New Record!!" — nothing motivates quite like beating yesterday's you. Your total correct answers and play time are saved too, so you can always look back on how far you've come. [A daily brain workout] A session takes just a few minutes. Do a set with your morning coffee or one before bed; it fits easily into any routine. A little practice every day is the surest way to get better at mental math. [Simple and focused] Large, easy-to-read numbers on a clean screen keep you focused on the problem in front of you. Customize the theme and sound to suit your style. Works on both iPhone and iPad. ■ GET STARTED IN 3 EASY STEPS 1. Pick a mode: addition, subtraction, multiplication, division, or Sums 2. Set the digits and the number of questions 3. Tap start! When you finish, you'll see your clear time and results That's it. You can start training the moment the mood strikes. ■ FAIR, SIMPLE PRICING Every mode and feature is free to use (with ads). Prefer to train without distractions? A single one-time purchase removes all banner and full-screen ads. No subscription, ever. Pay once and enjoy MathTre ad-free for good. Switching devices? Just tap "Restore Purchases." ■ START TODAY Your math skills grow with every bit of practice. Warm up your brain with one set a day on MathTre. Questions or ideas? Reach us anytime through the contact form in the app. We read every message and keep improving MathTre based on your feedback.

巧工是一座装进口袋的古代机械陈列馆：50 件中外古代机械与器物，全部以三维模型呈现；机器会自己运转，你也可以点穿外壳看内部。 【机器自己会转，不是预录动画】 每台机器按真实传动关系装配：入馆后水流驱动自行运转，立轮经锥齿轮增速带动主轴，三盘磨同时转动；曲柄牵杆往复、木扇一下下向炉膛鼓风。齿轮啮合、连杆往复、凸轮起落、刮板链循环都是运行时逐帧算出来的，不是预录动画。单指滑移是旋转视角、双指捏合是缩放，均为相机操作。 【点一下，看穿外壳】 点选任一零件：它被点亮，其余构件转为半透明，内部机构一次看清——藏在樽身的都柱、槽内循环的刮板链、仪象台顶的轮系。底部铭牌同步给出该零件的名称与作用；转速表按各件器物的额定传动比读数，纯往复件显示「次/分」而非「转/分」。 【两页解说：传动链 与 历史】 「传动链」逐件列出谁驱动谁；「历史」页写明年代、出处、背景与意义。 【形制有争议的，把争议摆出来】 木牛流马、司南、候风地动仪、水运浑天——史学界本无定说。这些器物内置多种复原假说，点标题下方的按钮即可切换对比，每一种都只是「一种可能」，不是标准答案。 【50 件器物 · 七个门类】 ・水利提水 · 动力（7）：筒车、水排、桔槔、辘轳、翻车、水转翻车、高转筒车 ・粮食加工（7）：水转连磨、连机碓、卧轮水磨、水碾、罗、风扇车、水转三事 ・纺织（6）：纺车、水转大纺车、大纺车、缫车、斜织机、花楼机 ・天文 · 计时 · 指示（5）：漏刻、简仪、记里鼓车、指南车、水运仪象台 ・世界古代（9）：罗马双列水磨、希罗汽转球、阿基米德螺旋泵、安提基特拉机械、机轴擒纵、塔楼天文钟、贾扎里象钟、双缸水泵、可编程乐手 ・争议 · 多假说（4）：木牛流马、司南、候风地动仪、水运浑天 ・百工器用（12）：走马灯、竹蜻蜓、车船、杆秤、算盘、陀螺、手磨、欹器、被中香炉、踏轮起重机、曲辕犁、风筝 【离线 · 零权限 · 无内购】 全部内容随 App 内置，不发起任何网络请求，飞行模式下完整可用；不申请定位、相机、麦克风、照片、运动等任何系统权限；无账号、无广告、无内购、无订阅，也没有需要恢复的购买。设置里可按机型选择画质档位（自动 / 高 / 中 / 低）。 【请把它当演示，不要当考据】 巧工是机构原理的互动演示物，不是考据成果：齿数、转速、比例与构件尺寸均为便于看懂机构的演示取值，不可作为复原数据引用。历史文字带有「确证 / 较可靠 / 推定 / 争议」四档置信度标注，尚未逐条核对原书图版与博物馆实物。 【运行要求】iOS 17 及以上。iPhone 竖屏；iPad 原生支持，横竖屏全屏自适应（藏品墙按屏宽自动 2–4 列）。 问题、纠错与建议：xappfactory-feedback@hotmail.com