數學練習 · 全新體驗
Series
把Series變成一場你真心想贏的對決。每一道題都是一次攻擊——比對手更快解出，就能命中對方。
4–99+ 歲皆宜 · 免下載 · 直接在瀏覽器中遊玩 · 23 種語言
玩法說明
Series
選一名鬥士，挑選Series，相信你的算術。解得越快、越準，出拳就越重——從輕鬆的低年級題目，一路挑戰到奧林匹亞等級。
A series is what you get when you add a sequence up. Adding evenly-spaced numbers one at a time is slow, and there is a much better way.
The story goes that a schoolboy named Gauss was told to add 1 to 100 and answered almost at once. He had noticed that the numbers pair up from the outside in: 1 + 100 = 101, 2 + 99 = 101, 3 + 98 = 101. Fifty pairs, each worth 101, giving 5050.
The general rule is the same idea: S = n × (a₁ + aₙ) ÷ 2. Read it as "how many terms, times the average of the first and the last", because in an evenly-spaced list the average really is just the midpoint of the two ends.
Add the first and last term, multiply by the number of terms, halve it, and type the sum.
— 快問快答 —
Series：精簡 FAQ
- Series可以免費玩嗎？
- 可以。Series在瀏覽器裡就能免費暢玩——課程全部開放，免下載、免註冊。付費方案之後才解鎖完整鬥士陣容、全部舞台與進度保存。
- Series適合誰玩？
- 4 到 99+ 歲的任何人。低年級對新手依然平緩，更高的難度則連有自信的玩家也得冒汗。
- 玩Series需要下載什麼嗎？
- 不需要。Series在任何瀏覽器裡都能跑，筆電、平板或手機都行。
- Series能在課堂上用嗎？
- 當然可以。老師帶一整班玩Series，還能追蹤誰在進步——按學生人數計價與教師儀表板，詳見學校方案。