Name: 不用計算機也能秒算！心算秘訣大公開！ (How to Calculate Faster than a Calculator - Mental Math #1)
Uploaded: 2025-09-21T21:01:20.000Z
Duration: 5 min 5 s

情態助動詞 A2

Before we start this video, in five seconds can you quickly tell me how much is 86 times 84?

在我們開始播放影片之前，你能在 5 秒鐘內快速告訴我 86 乘以 84 等於多少嗎？

基礎數量詞

I know many of you would have struggled to find it in five seconds,

我知道你們中的很多人都很難在五秒鐘內算出答案，

but I am making a series of mental math videos, and after completing this series, nd with a bit of practice,

但我正在製作一系列心算影片，看完這一系列影片後，再稍加練習，

you will be able to do calculations like these faster than a calculator, that is at a lightning fast speed.

你就能以快如閃電的速度完成這樣的計算，比計算機還快。

Yes, even faster than the snap of Thanos, and you will be able to amaze your friends and appear smarter in front of them.

是的，甚至比薩諾斯的反應還要快，你將能讓你的朋友大吃一驚，並在他們面前顯得更加聰明。

We will first start with the very basic, which is multiplying any two-digit number with 11.

我們先從最基本的開始，即任何兩位數乘以 11。

Yeah, I know we can use the method we had learned in school, but it will be a bit longer.

是的，我知道我們可以用在學校學到的方法，但時間會比較長。

But using this trick, it will be super fast.

但使用這一招，速度會超級快。

So write 4 and 3, and in the center write 4 plus 3 or 7.

所以寫 4 和 3，中間寫 4 加 3 或 7。

Although it's basic, but it's super fast.

Write 5 and 4, and in between write 5 plus 4 or 9.

But you might wonder, what if the sum is greater than or equal to 10?

但你可能會問，如果總和大於或等於 10 呢？

Write 6 then 8, and in the middle it will be 6 plus 8 or 14.

先寫 6，再寫 8，中間就是 6 加 8 或 14。

So take 1 to the carry, and add with 6 to make it 7.

所以把 1 去掉，再與 6 相加就是 7。

Now, you might be thinking that I am sharing tricks only for specific numbers, but that's not mental math.

現在，你可能會認為我只是針對特定的數字分享技巧，但這並不是心算。

This is only the beginning, as this is the first part.

這只是開始，因為這是第一部分。

Now, the trick I taught you also works with three-digit numbers.

現在，我教你的訣竅同樣適用於三位數。

Now in center first, add both of them to get 8, and now add 5 plus 2 or 7 here.

現在在中間的第一個位置，將這兩個數字相加得到 8，然後在這裡加上 5 加 2 或 7。

And if the sum is greater than 9, then just carry like the previous one.

如果總和大於 9，就像前一個一樣進行運算。

So write 5 and 4 here, then in the middle write 5 plus 7 or 12, and here 7 plus 4 or 11.

所以在這裡寫 5 和 4，然後在中間寫 5 加 7 或 12，這裡寫 7 加 4 或 11。

Now carry 1 here to make it 6, and then carry 1 here to make it 3.

現在把 1 搬到這裡，變成 6，再把 1 搬到這裡，變成 3。

Now, let us move to the next trick, which is multiplying two two-digit numbers with the same first digit and ending in 5, like multiply 75 times 75 in 5 seconds.

現在，讓我們進入下一個小竅門，即兩個兩位數相乘，首數相同且尾數為 5，比如在 5 秒內乘以 75 乘以 75。

So the trick here is to multiply 7 with the next number or 8 to get 56, and then simply add 25 to it.

這裡的訣竅就是用 7 乘以下一個數字或 8，得到 56，然後再簡單地加上 25。

Okay, now try 35 times 35. 3 times 4 is 12, and then add 25.

好，現在試試 35 乘以 35。3 乘以 4 是 12，然後再加上 25。

Now tell me in the comments what will be 95 times 95.

現在請在評論中告訴我 95 乘以 95 的結果是什麼。

It is multiplying two two-digit numbers with the same first digit of both the numbers, and the sum of the ending digits is 10.

它是兩個兩位數相乘，兩個數的首位數字相同，末位數字之和為 10。

Here the first digit of both the numbers are the same, which is 4, and the sum of the ending digits is 4 plus 6 or 10.

在這裡，兩個數字的首位數字相同，都是 4，末位數字之和是 4 加 6 或 10。

Now do 4 times its next number, or 5, which is 20, and then 4 times 6 or 24.

現在做 4 乘以它的下一個數字，即 5，也就是 20，然後做 4 乘以 6，即 24。

Now let us try 67 times 63. 6 times 7 is 42, and 7 times 3 is 21.

現在讓我們試試 67 乘以 63。6 乘以 7 是 42，7 乘以 3 是 21。

We're still beating calculators in speed.

在速度方面，我們仍在不斷超越計算器。

Okay, now tell me in the comments what will be the value of 89 times 81.

好了，現在請在評論中告訴我 89 乘以 81 的值是多少。

You are already doing calculations faster, like a human calculator.

你的計算速度已經更快了，就像人類的計算器一樣。

Lastly, don't forget to practice this trick, and you'll get even faster.

最後，別忘了練習這一招，你會變得更快。

If I get 10,000 likes in this video, I will make part 2 of it, which will be much more interesting and super fun.

如果這部影片獲得 10,000 個讚，我就會製作第二部，這部會更有趣、更好玩。

字幕列表影片播放

不用計算機也能秒算！心算秘訣大公開！ (How to Calculate Faster than a Calculator - Mental Math #1)

specific

struggle

mental

awesome