What is 50 by 5 = 10 that's easy but what is 3421 by 5. It's not that easy to calculate in mind right? What is the sum of all even numbers from 0 to 10.
Now, there are 4 even numbers between 0 and 10.
Which are 2, 4, 6 and 8.
Let's visualize these numbers.
So, what have I got here is a rectangle of 4 into 5 which is 20. And guess the formula i.e. n + 1.
Now try it with odd numbers. It's not exactly this formula but it's something different.
i.e. square numbers
The sum of the first n odd number is n2.
Let's remember 5 is 10/2 so, How about if we first divide this by 10 So, 3421 divided by 10 is 342.1 and now I can multiply this by 2 . I've got 684.2. Wasn't that quick enough?
What is 50 by 5 = 10 that's easy but what is 3421 by 5.
It's not that easy to calculate in mind right?
What is the sum of all even numbers from 0 to 10.
Now, there are 4 even numbers between 0 and 10.
Which are 2, 4, 6 and 8.
Let's visualize these numbers.
So, what have I got here is a rectangle of 4 into 5 which is 20. And guess the formula i.e. n + 1.
Now try it with odd numbers. It's not exactly this formula but it's something different.
i.e. square numbers
The sum of the first n odd number is n2.
Let's remember 5 is 10/2 so,
How about if we first divide this by 10
So, 3421 divided by 10 is 342.1 and now I can multiply this by 2 . I've got 684.2. Wasn't that quick enough?
https://www.englishmaths.in/2021/11/maths-tricks-for-fast-calculation.html
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