一、加法不一定逐步數
上一課我們學了：13Please respect copyright.ＰＥＮＡＮＡzbf3XHs0R0
> 8 + 313Please respect copyright.ＰＥＮＡＮＡIUuJwocGYy
可以由 8 開始接住數：13Please respect copyright.ＰＥＮＡＮＡrsAkt6YtML
> 8 → 9 → 10 → 11
所以：13Please respect copyright.ＰＥＮＡＮＡDbE5RSLGnV
> 8 + 3 = 1113Please respect copyright.ＰＥＮＡＮＡLYmn5F5wd6
這個方法很有用。
但如果數字再大一些，每次都一步一步數，仍然會慢。
例如：13Please respect copyright.ＰＥＮＡＮＡSNIjnmkIBW
> 8 + 713Please respect copyright.ＰＥＮＡＮＡILQShCfGUm
你可以由 8 開始數 7 步，但有沒有更聰明的方法？
今課我們會開始找加法規律，尤其是一個很重要的技巧：13Please respect copyright.ＰＥＮＡＮＡPnnBOab1N0
> 湊十 | Making Ten13Please respect copyright.ＰＥＮＡＮＡJFpk8DU3eB
二、為何 10 很重要？
我們日常用的數字系統很依賴 10。
例如：13Please respect copyright.ＰＥＮＡＮＡHpHUJu4NVU
> 10、20 、30、100、100013Please respect copyright.ＰＥＮＡＮＡ97hBedy4Q5
好多大數都是圍繞 10 而建立。
所以如果你熟悉哪些數可以湊成 10，之後做加法會快好多。
例如：13Please respect copyright.ＰＥＮＡＮＡhrE7s9kN9d
> 8 + 2 = 1013Please respect copyright.ＰＥＮＡＮＡ9hw5mNw01S
> 7 + 3 = 1013Please respect copyright.ＰＥＮＡＮＡK46gxsw6Av
> 6 + 4 = 1013Please respect copyright.ＰＥＮＡＮＡmVyZxVtMmp
> 5 + 5 = 1013Please respect copyright.ＰＥＮＡＮＡuAZZFJUx4O
這些叫：13Please respect copyright.ＰＥＮＡＮＡWLhG1ar5CA
> 湊十組合 | Number bonds to 1013Please respect copyright.ＰＥＮＡＮＡrrPkbsBDMh
可以理解成：13Please respect copyright.ＰＥＮＡＮＡrH0XwlUZUt
> 兩個部分合起來，剛好成為 10。13Please respect copyright.ＰＥＮＡＮＡOxcRhJCcpX
三、先記住 10 的組合
以下是最基本的湊十組合：13Please respect copyright.ＰＥＮＡＮＡMD1ADUUw05
> 0 + 10 = 1013Please respect copyright.ＰＥＮＡＮＡSwY2pBiB0S
> 1 + 9 = 1013Please respect copyright.ＰＥＮＡＮＡ1ruqAJ1dYE
> 2 + 8 = 1013Please respect copyright.ＰＥＮＡＮＡImMryL2SKb
> 3 + 7 = 1013Please respect copyright.ＰＥＮＡＮＡ2Xbh6FDByP
> 4 + 6 =1013Please respect copyright.ＰＥＮＡＮＡPb8xp8gvAN
> 5 + 5 = 1013Please respect copyright.ＰＥＮＡＮＡvj46mdT2Ki
> 6 + 4 = 1013Please respect copyright.ＰＥＮＡＮＡDTtavICQdr
> 7 + 3 = 1013Please respect copyright.ＰＥＮＡＮＡWiWs3psO7r
> 8 + 2 = 1013Please respect copyright.ＰＥＮＡＮＡSuqolGz3W8
> 9 + 1 = 1013Please respect copyright.ＰＥＮＡＮＡmFrmN3ZJgQ
> 10 + 0 = 1013Please respect copyright.ＰＥＮＡＮＡu7RDbKdgZd
你會見到：13Please respect copyright.ＰＥＮＡＮＡZm5inolaGF
> 1 配 913Please respect copyright.ＰＥＮＡＮＡSBdVl7Aa7a
> 2 配 813Please respect copyright.ＰＥＮＡＮＡdsOt3WSpBh
> 3 配 713Please respect copyright.ＰＥＮＡＮＡ5qEF56zdR3
> 4 配 613Please respect copyright.ＰＥＮＡＮＡIvBNjmDQCG
> 5 配 513Please respect copyright.ＰＥＮＡＮＡqINkQdFejH
如果交換次序，答案仍然一樣。
例如：13Please respect copyright.ＰＥＮＡＮＡYmXG2zPvxQ
> 3 + 7 = 1013Please respect copyright.ＰＥＮＡＮＡoikbClFzet
> 7 + 3 = 1013Please respect copyright.ＰＥＮＡＮＡtIJNnDaIRB
四、簡單例子：直接湊十
例子 1：8 + 213Please respect copyright.ＰＥＮＡＮＡu5n952alqR
8 距離 10 差幾多？13Please respect copyright.ＰＥＮＡＮＡITtNtiXxnH
> 8 → 9：第 1 步13Please respect copyright.ＰＥＮＡＮＡaKVeeyIBgB
> 9 → 10：第 2 步13Please respect copyright.ＰＥＮＡＮＡ5tBSin21s6
所以 8 差 2 到 10。
因此：13Please respect copyright.ＰＥＮＡＮＡxfUmLD6IfN
> 8 + 2 = 1013Please respect copyright.ＰＥＮＡＮＡgEDHXNj09n
//
例子 2：6 + 4
6 距離 10 差幾多？13Please respect copyright.ＰＥＮＡＮＡTKACLshYO3
> 6 → 7：第 1 步13Please respect copyright.ＰＥＮＡＮＡZzASsFxsiC
> 7 → 8：第 2 步13Please respect copyright.ＰＥＮＡＮＡmSViO2YYzw
> 8 → 9：第 3 步13Please respect copyright.ＰＥＮＡＮＡM1QPPliIyt
> 9 → 10：第 4 步13Please respect copyright.ＰＥＮＡＮＡ3LsEctBF59
所以 6 差 4 到 10。
因此：13Please respect copyright.ＰＥＮＡＮＡwR821UxEOZ
> 6 + 4 = 1013Please respect copyright.ＰＥＮＡＮＡ4duEUfDspF
//
例子 3：9 + 1
9 只差 1 就到 10：13Please respect copyright.ＰＥＮＡＮＡwhjyoceRYf
> 9 → 1013Please respect copyright.ＰＥＮＡＮＡuw5tqlXuHF
所以：13Please respect copyright.ＰＥＮＡＮＡcE4nVXSmfs
> 9 + 1 = 1013Please respect copyright.ＰＥＮＡＮＡupUWeNmjps
五、湊十如何幫助加法？
如果題目是：13Please respect copyright.ＰＥＮＡＮＡw0egi9ex3t
> 8 + 513Please respect copyright.ＰＥＮＡＮＡ0HkttBs29q
你可以逐步數：13Please respect copyright.ＰＥＮＡＮＡskh5o8jqfh
> 8 → 9 → 10 → 11 → 12 → 1313Please respect copyright.ＰＥＮＡＮＡxeltt30Ixq
答案是 13。
但湊十可以令思考更清楚。
步驟 1：先問 8 差幾多到 1013Please respect copyright.ＰＥＮＡＮＡWldHXCMHWj
> 8 差 2 到 10
所以將 5 拆開成：13Please respect copyright.ＰＥＮＡＮＡzZjqzU26gP
> 2 + 313Please respect copyright.ＰＥＮＡＮＡd7tpdUPWDq
因為：13Please respect copyright.ＰＥＮＡＮＡOZzeAZZ9Tx
> 5 = 2 + 313Please respect copyright.ＰＥＮＡＮＡtTn67t0SPC
步驟 2：先用 2 湊成 1013Please respect copyright.ＰＥＮＡＮＡWxAqiTaGIa
> 8 + 2 = 1013Please respect copyright.ＰＥＮＡＮＡ2RvhmdfiUx
步驟 3：再加剩低的 313Please respect copyright.ＰＥＮＡＮＡXaOf7CsAa0
> 10 + 3 = 1313Please respect copyright.ＰＥＮＡＮＡ0nCKHy5nuP
所以：13Please respect copyright.ＰＥＮＡＮＡ6CHpOm2Uiw
> 8 + 5 = 1313Please respect copyright.ＰＥＮＡＮＡ9U3O9E0jZ5
完整想法：13Please respect copyright.ＰＥＮＡＮＡBDlegCWPrF
> 8 + 513Please respect copyright.ＰＥＮＡＮＡsBGKjiykCj
> = 8 + 2 + 313Please respect copyright.ＰＥＮＡＮＡ4k19o8p8R3
> = 10 + 313Please respect copyright.ＰＥＮＡＮＡishvgxicQa
> = 1313Please respect copyright.ＰＥＮＡＮＡtldszMYKaA
湊十的核心是：13Please respect copyright.ＰＥＮＡＮＡX4lNwrkYQH
> 先去到 10，再接住加剩低那部分。
六、數字拆分：將一個數分成兩部分
要湊十，通常要將一個數拆開。13Please respect copyright.ＰＥＮＡＮＡkXmwNTj84v
例如：13Please respect copyright.ＰＥＮＡＮＡKFGWub5Jhm
> 5 可以拆成 2 + 313Please respect copyright.ＰＥＮＡＮＡJdRpbkBPXX
> 6 可以拆成 1 + 513Please respect copyright.ＰＥＮＡＮＡ7W7gN1tgty
> 7 可以拆成 2 + 513Please respect copyright.ＰＥＮＡＮＡ4RrCjGYevm
> 4 可以拆成 1 + 313Please respect copyright.ＰＥＮＡＮＡv47u4RFsiM
拆分不代要改變數量，只是將同一個數分成兩部分。
例如 5 粒糖果：13Please respect copyright.ＰＥＮＡＮＡnNOKJk2wCA
> 🍬 🍬 | 🍬 🍬 🍬13Please respect copyright.ＰＥＮＡＮＡWg9dkMOwOJ
左邊 2 粒，右邊 3 粒。
所以：13Please respect copyright.ＰＥＮＡＮＡsZsJB3ttss
> 5 = 2 + 313Please respect copyright.ＰＥＮＡＮＡclu28CkmNX
但總數仍然是 5。
七：簡單例子：9 + 4
問題：13Please respect copyright.ＰＥＮＡＮＡYqLMO9VcFs
> 9 + 4= ?13Please respect copyright.ＰＥＮＡＮＡrTGHiCSD93
步驟 1：9 差幾多到 10？13Please respect copyright.ＰＥＮＡＮＡlA8Vk1D37D
> 9 差 1 到 10
步驟 2：將 4 拆成 1 + 313Please respect copyright.ＰＥＮＡＮＡJJ8XJaqPvD
> 4 = 1 + 3
步驟 3：先湊十13Please respect copyright.ＰＥＮＡＮＡY5T6OwXACC
> 9 + 1 = 1013Please respect copyright.ＰＥＮＡＮＡmXqw8IlTkl
步驟 4：再加剩低的 313Please respect copyright.ＰＥＮＡＮＡEcFmysnJbI
> 10 + 3 = 1313Please respect copyright.ＰＥＮＡＮＡ7sBYHkXxfx
所以：13Please respect copyright.ＰＥＮＡＮＡXHMq9HZUrq
> 9 + 4 = 1313Please respect copyright.ＰＥＮＡＮＡDuQjXkpGUi
完整：13Please respect copyright.ＰＥＮＡＮＡdomLwi0BEM
> 9 + 413Please respect copyright.ＰＥＮＡＮＡVrTFcbtFnJ
> = 9 + 1 + 313Please respect copyright.ＰＥＮＡＮＡNdEqSwQKGu
> = 10 + 313Please respect copyright.ＰＥＮＡＮＡ5NJwpE85ye
> = 1313Please respect copyright.ＰＥＮＡＮＡMxsrPkHQdz
八、7 + 5
問題：13Please respect copyright.ＰＥＮＡＮＡJC5f7KiYyl
> 7 + 5 = ?13Please respect copyright.ＰＥＮＡＮＡozTcHyzxjR
步驟 1：7 差幾多到 10？13Please respect copyright.ＰＥＮＡＮＡ6y0SgBrVCQ
由 7 到 10：13Please respect copyright.ＰＥＮＡＮＡFXdXJSvFhT
> 7 → 8：第 1 步13Please respect copyright.ＰＥＮＡＮＡqZRVohjszH
> 8 → 9：第 2 步13Please respect copyright.ＰＥＮＡＮＡsMDMSdejPO
> 9 → 10：第 3 步13Please respect copyright.ＰＥＮＡＮＡNw5BkMISI1
所以：13Please respect copyright.ＰＥＮＡＮＡMI05LH5uYj
> 7 差 3 到 1013Please respect copyright.ＰＥＮＡＮＡxffvcW40uS
步驟 2：將 5 拆成 3 + 213Please respect copyright.ＰＥＮＡＮＡHZhTXQyald
> 5 = 3 + 213Please respect copyright.ＰＥＮＡＮＡ7km3bs2P6j
步驟 3：先湊十13Please respect copyright.ＰＥＮＡＮＡiFmxRgovyH
> 7 + 3 = 1013Please respect copyright.ＰＥＮＡＮＡNAtFoUEERi
步驟 4：再加剩低的 213Please respect copyright.ＰＥＮＡＮＡA6dSBbH2lS
> 10 + 2 = 1213Please respect copyright.ＰＥＮＡＮＡmukfJ7vt5W
所以：13Please respect copyright.ＰＥＮＡＮＡEUp1HqzEsB
> 7 + 5 =1213Please respect copyright.ＰＥＮＡＮＡkr2W2t5zHB
九、6 + 8
問題：13Please respect copyright.ＰＥＮＡＮＡISquLX45Qw
> 6 + 8 = ?13Please respect copyright.ＰＥＮＡＮＡXgR13L5bj8
這條題目有兩個方向。
方向 A：由 6 湊十13Please respect copyright.ＰＥＮＡＮＡOCYvvkk3BF
6 差 4 到 10。13Please respect copyright.ＰＥＮＡＮＡAAyXudkq35
所以將 8 拆成：13Please respect copyright.ＰＥＮＡＮＡykDReo5K5E
> 4 + 4
然後：13Please respect copyright.ＰＥＮＡＮＡpaEGCrmWfD
> 6 + 813Please respect copyright.ＰＥＮＡＮＡHUu0X6nEtH
> = 6 + 4 + 413Please respect copyright.ＰＥＮＡＮＡHxtbVmVbp0
> = 10 + 413Please respect copyright.ＰＥＮＡＮＡhyu9peIAqw
> = 1413Please respect copyright.ＰＥＮＡＮＡBWcmbVK2EV
答案：13Please respect copyright.ＰＥＮＡＮＡZ4zSu9wlmC
> 1413Please respect copyright.ＰＥＮＡＮＡXRa5A098zk
//
方法 B：由 8 湊十13Please respect copyright.ＰＥＮＡＮＡbWTUlcNC76
8 差 2 到 10。
所以將 6 拆成：13Please respect copyright.ＰＥＮＡＮＡ0aGytPo6gF
> 2 + 413Please respect copyright.ＰＥＮＡＮＡ6nNOfdo8Yr
然後：13Please respect copyright.ＰＥＮＡＮＡwnM5PGYQ8g
> 8 + 613Please respect copyright.ＰＥＮＡＮＡ6CTCHpxx1A
> = 8 + 2 + 413Please respect copyright.ＰＥＮＡＮＡUs397uFsHh
> = 10 + 413Please respect copyright.ＰＥＮＡＮＡq6ghcDhEP8
> = 14
答案一樣13Please respect copyright.ＰＥＮＡＮＡrG63G2Ll48
> 1413Please respect copyright.ＰＥＮＡＮＡnhRrGZ0SxZ
//
哪個方法更自然？13Please respect copyright.ＰＥＮＡＮＡhX8sX2Dq7i
通常由較接近 10 的數開始會容易一些。13Please respect copyright.ＰＥＮＡＮＡHxxI7WDMNs
8 比 6 更接近 10，所以：13Please respect copyright.ＰＥＮＡＮＡGBX4WoCdrw
> 8 + 613Please respect copyright.ＰＥＮＡＮＡakXhonJnxI
會比較容易思考：13Please respect copyright.ＰＥＮＡＮＡCL7v4gpRZe
> 8 差 2，到 10，再剩 4。13Please respect copyright.ＰＥＮＡＮＡciKlqR76Ic
所以：13Please respect copyright.ＰＥＮＡＮＡtnYBaQA9gd
> 8 + 6 = 1413Please respect copyright.ＰＥＮＡＮＡlyh1IO3G9v
十、加法規律：雙倍
有一類加法特別容易記：13Please respect copyright.ＰＥＮＡＮＡpDTmuC2S58
> 1 + 1 = 213Please respect copyright.ＰＥＮＡＮＡpZTIKr6mGd
> 2 + 2 = 413Please respect copyright.ＰＥＮＡＮＡnIZ52tWJ3v
> 3 + 3 = 613Please respect copyright.ＰＥＮＡＮＡzRNRkTfa0A
> 4 + 4 = 813Please respect copyright.ＰＥＮＡＮＡqQrzJ7zjEF
> 5 + 5 = 1013Please respect copyright.ＰＥＮＡＮＡ1N8KoZUdCl
> 6 + 6 = 1213Please respect copyright.ＰＥＮＡＮＡpWFM7tTZmg
> 7 + 7 = 1413Please respect copyright.ＰＥＮＡＮＡ6BVjSaFZ6m
> 8 + 8 = 1613Please respect copyright.ＰＥＮＡＮＡ9ey8Q31m4T
> 9 + 9 = 1813Please respect copyright.ＰＥＮＡＮＡWDgUjoxL5d
> 10 + 10 = 2013Please respect copyright.ＰＥＮＡＮＡwmSk2j8pJf
這些叫：13Please respect copyright.ＰＥＮＡＮＡROLJhmKPuV
> 雙倍數 | Doubles13Please respect copyright.ＰＥＮＡＮＡimfvfCfrUi
意思是：13Please respect copyright.ＰＥＮＡＮＡPUIu2MR5F6
> 同一個數加自己。13Please respect copyright.ＰＥＮＡＮＡrRY0uSYbry
例如：13Please respect copyright.ＰＥＮＡＮＡwSWGbm3eMw
> 6 + 6 = 12
雙倍數加法很重要，因為好多加法都可以靠近它。
十一、接近雙倍數：Near Doubles
例如：13Please respect copyright.ＰＥＮＡＮＡKdFH3S3NBX
> 6 + 713Please respect copyright.ＰＥＮＡＮＡnk7QGpsJi8
7 比 6 多 1。
你可以先想：13Please respect copyright.ＰＥＮＡＮＡtvjiqFsYHr
> 6 + 6 = 1213Please respect copyright.ＰＥＮＡＮＡNcUw7ao0K9
再加 1：13Please respect copyright.ＰＥＮＡＮＡo2542jvbH7
> 12 + 1 = 13
所以：13Please respect copyright.ＰＥＮＡＮＡSjVQYWyEos
> 6 + 7 = 1313Please respect copyright.ＰＥＮＡＮＡysdFerPgpX
//
又例如：13Please respect copyright.ＰＥＮＡＮＡPAXm72sCer
> 8 + 913Please respect copyright.ＰＥＮＡＮＡ06hqTPL4A5
先想：13Please respect copyright.ＰＥＮＡＮＡrrlQxkdg77
> 8 + 8 = 1613Please respect copyright.ＰＥＮＡＮＡbfkC1Kv0ad
再多 1：13Please respect copyright.ＰＥＮＡＮＡDcH25Bumrq
> 16 + 1 = 1713Please respect copyright.ＰＥＮＡＮＡP5RroZmM8G
所以：13Please respect copyright.ＰＥＮＡＮＡJ2JLR8fUEk
> 8 + 9 = 1713Please respect copyright.ＰＥＮＡＮＡZJPnj9Y6IW
這個叫：13Please respect copyright.ＰＥＮＡＮＡP08AOGWGIR
> 接近雙倍數 | Near Doubles13Please respect copyright.ＰＥＮＡＮＡBu7vR5QYWz
即是：13Please respect copyright.ＰＥＮＡＮＡDe8IFCg4gr
> 兩個數差 1，可以先用雙數，再調整 1。13Please respect copyright.ＰＥＮＡＮＡeW5H4dmpHr
十二、7 + 8
問題：13Please respect copyright.ＰＥＮＡＮＡssoeOU1adf
> 7 + 8 = ?13Please respect copyright.ＰＥＮＡＮＡRH4ET1mhHO
可以用湊十，也可以用接近雙倍數。
方法 A：13Please respect copyright.ＰＥＮＡＮＡA4Bm9jadiN
8 差 2 到 10：13Please respect copyright.ＰＥＮＡＮＡl66owlnHXc
將 7 拆成：13Please respect copyright.ＰＥＮＡＮＡkVOuYt7qmh
> 2 + 513Please respect copyright.ＰＥＮＡＮＡzZECilcGl1
所以：13Please respect copyright.ＰＥＮＡＮＡQ8IujL0IP3
> 8 + 713Please respect copyright.ＰＥＮＡＮＡkI4LpTY9L1
> = 8 + 2 + 513Please respect copyright.ＰＥＮＡＮＡ4Iphw0F6pY
> = 10 + 513Please respect copyright.ＰＥＮＡＮＡAPvk7sm3L2
> = 1513Please respect copyright.ＰＥＮＡＮＡn7fkmlDszl
//
方法 B：接近雙倍數13Please respect copyright.ＰＥＮＡＮＡvObMxamr94
先想：13Please respect copyright.ＰＥＮＡＮＡfgnEVIDVXg
> 7 + 7 = 1413Please respect copyright.ＰＥＮＡＮＡ00KO7cNhLZ
而 8 比 7 多 1。
所以：13Please respect copyright.ＰＥＮＡＮＡO61mSa9D9s
> 7 + 8 = 1513Please respect copyright.ＰＥＮＡＮＡiQl5TLc2Dj
兩個方法都對。
重點是：13Please respect copyright.ＰＥＮＡＮＡAK0Zdev5Md
> 數學可以有多一條合理解題路線。13Please respect copyright.ＰＥＮＡＮＡP2A5Wh1Ijd
十三、加 9 的規律
加 9 可以用很有效率地湊 10。13Please respect copyright.ＰＥＮＡＮＡ73LqMSittK
例如：13Please respect copyright.ＰＥＮＡＮＡfqCCSBy3qo
> 6 + 913Please respect copyright.ＰＥＮＡＮＡednERLrxFS
9 差 1 到 10。
可以由 6 借 1 給 9：13Please respect copyright.ＰＥＮＡＮＡl1JQERtsDt
> 9 + 1 = 1013Please respect copyright.ＰＥＮＡＮＡWQaInC3w4g
6 借走 1 之後剩：13Please respect copyright.ＰＥＮＡＮＡMAUuxERV7P
> 513Please respect copyright.ＰＥＮＡＮＡbN62oKRIc4
所以：13Please respect copyright.ＰＥＮＡＮＡYXiDBs05bt
> 6 + 913Please respect copyright.ＰＥＮＡＮＡUWE37SXk6M
> = 5 + 1013Please respect copyright.ＰＥＮＡＮＡJT7wXqgYFF
> = 1513Please respect copyright.ＰＥＮＡＮＡaMxm3acOp6
另一個寫法：13Please respect copyright.ＰＥＮＡＮＡxigYZ5ddGw
> 9 + 613Please respect copyright.ＰＥＮＡＮＡRdJw5lDaXm
> = 9 + 1 + 513Please respect copyright.ＰＥＮＡＮＡYOohVg3N0y
> = 10 + 513Please respect copyright.ＰＥＮＡＮＡ7b3nfG3GvQ
> = 1513Please respect copyright.ＰＥＮＡＮＡzXJpWZgGai
加 9 的直覺可以是：13Please respect copyright.ＰＥＮＡＮＡvWHkJ9g4jr
> 加 10 再少 113Please respect copyright.ＰＥＮＡＮＡRurXDbC3ba
例如：13Please respect copyright.ＰＥＮＡＮＡQ2TwgIHbEc
> 6 + 10 = 1613Please respect copyright.ＰＥＮＡＮＡNUzDlA0otW
> 6 + 9 = 1513Please respect copyright.ＰＥＮＡＮＡNH5JBPPLif
因為 9 比 10 少 1。
十四、加法規律不是魔法
今課有很多技巧：13Please respect copyright.ＰＥＮＡＮＡd0NEGYNmND
> 湊十、雙倍數、接近雙倍數、加 913Please respect copyright.ＰＥＮＡＮＡ7I6cTZbnR2
但所技巧都要回到同一個基礎：13Please respect copyright.ＰＥＮＡＮＡ2OFIkHErpF
> 數量沒有改變，只是拆分與重組。13Please respect copyright.ＰＥＮＡＮＡbsu95M15hj
例如：13Please respect copyright.ＰＥＮＡＮＡ4c7QshDnia
> 8 + 513Please respect copyright.ＰＥＮＡＮＡNxrSYEOM2x
改成：13Please respect copyright.ＰＥＮＡＮＡCRieMMk3yr
> 8 + 2 + 313Please respect copyright.ＰＥＮＡＮＡj67BM3kR0X
這裏沒有偷偷地改答案，因為：13Please respect copyright.ＰＥＮＡＮＡBiKL2Gxjlx
> 5 = 2 + 313Please respect copyright.ＰＥＮＡＮＡDJst0FAlgO
數學技巧可靠，因為每一步都保持數量相等。
十五、綜合例子：選擇一個好方法
題目 1：9 + 713Please respect copyright.ＰＥＮＡＮＡoT3hP9rlE7
9 接近 10，所以用湊十。
9 差 1 到 10。13Please respect copyright.ＰＥＮＡＮＡs6Z2oxhDcL
將 7 拆成：13Please respect copyright.ＰＥＮＡＮＡlwy4BBvrCp
> 1 + 613Please respect copyright.ＰＥＮＡＮＡbRFW4NZLUX
所以：13Please respect copyright.ＰＥＮＡＮＡvAoVhYj6ih
> 9 + 713Please respect copyright.ＰＥＮＡＮＡKPMrWCGIV5
> = 9 + 1 + 613Please respect copyright.ＰＥＮＡＮＡx7Ch4N8gJp
> = 10 + 613Please respect copyright.ＰＥＮＡＮＡfzxlEWcDgd
> = 1613Please respect copyright.ＰＥＮＡＮＡBFN74AybmW
答案：13Please respect copyright.ＰＥＮＡＮＡfbTHDL5DFH
> 1613Please respect copyright.ＰＥＮＡＮＡZkWIZfi41s
//
題目 2：6 + 613Please respect copyright.ＰＥＮＡＮＡ4jyhknhjw1
兩個數一樣，用雙倍數：13Please respect copyright.ＰＥＮＡＮＡRxKw1ydGvj
> 6 + 6 = 1213Please respect copyright.ＰＥＮＡＮＡKLXTLVKAhm
答案：13Please respect copyright.ＰＥＮＡＮＡXGOf3Hx5nU
> 1213Please respect copyright.ＰＥＮＡＮＡKJIVTW6GOq
//
題目 3：6 + 713Please respect copyright.ＰＥＮＡＮＡ1oczt48tdC
兩個數差 1，用接近雙倍數13Please respect copyright.ＰＥＮＡＮＡiFCsa19wHT
> 6 + 6 = 1213Please respect copyright.ＰＥＮＡＮＡKTXvfFoqN4
> 再多 1 = 13
所以：13Please respect copyright.ＰＥＮＡＮＡjTM867oro4
> 6 + 7 = 1313Please respect copyright.ＰＥＮＡＮＡfYkuhHiZlA
十六、今日小結
今課你掌握了：13Please respect copyright.ＰＥＮＡＮＡjVCcScWb1U
1. 10 是重要標準，熟悉湊十可以加法更法。13Please respect copyright.ＰＥＮＡＮＡvUGXFsITFr
2. 湊十組合包括：1 + 9、2 + 8、3 + 7、4 + 6、5 + 5。13Please respect copyright.ＰＥＮＡＮＡhgzAyP3X5s
3. 做湊十時，可以將一個數拆成兩部分。13Please respect copyright.ＰＥＮＡＮＡ4RYCy17QgS
4. 例如 8 + 5 可以想成 8 + 2 + 3 = 10 + 3 = 13。13Please respect copyright.ＰＥＮＡＮＡo82jeUTRha
5. 雙倍數加法是同一個數加自己，例如 6 + 6 = 12。13Please respect copyright.ＰＥＮＡＮＡYVEDQZH4cF
6. 接近雙倍數可以先用雙倍數，再多一或少一。13Please respect copyright.ＰＥＮＡＮＡ1evHWH0TPq
7. 所有加法技巧都要保持原本數量不變。
湊十是將加法重新安排，先去到 10，再從 10 繼續前進。
ns216.73.216.75da2
and then Add to home screen.