Great stuff on this page. I trying to find the sum of the even numbers 6 – 100. Any help would be great.
@C. Mitchell: You can try doing this:
Sum of evens 6-100 is same as 2 x (sum of 3,4,5,6,… 50).
And to add 3…50, you can just add 1…50 and remember to subtract off the first 2 numbers (1+2). So 3-50 is [50*51/2 - 3], and multiply the whole thing by 2 to make it 6-100.
Hi, I like to know who made this formel first time, and when? thank U.
Hey thanks for this article- it’s helped me heaps with my year 7 assignment 
Is there any method to find n digit numbers which are both perfect and perfect cube
sana may 3 add number that came before 30
Hi im trying to use this equation to ad from 5 to 705 eg
350 * (700 + 5) = 246,750
Is this correct?
Interesting observations.
actually i have my own formula to add all numbers from 2-100 … w/c is much easy for me…
heres the formula…
Hxh+(Lxh)
H=highest number
L=lowest number
h=half of the numbers u want to add
(in “h”…example u want to add all numbers from
2-10…it means u will add 9 numbers…divide it in 2= 4.5)
example…
add all numbers from 2-10
(the answer should be 54)
formula
Hxh+(Lxh)
= 10x4.5+(2x4.5)
= 45+9
= 54 . . .
^^
hope this will help u ^^
I didn’t understand it so much but i’ll leave this question, please answer this; 14+21+28+35+42…6286+6293?
While it may be true that you can apply these explanations to other sets, you need not do so for the Fibonacci sequence. There are formulas for the Fibonacci sequence. One of them is easy: to calculate the nth number, raise Phi, the golden number, to the nth power, then divide by the square root of 5. Round the result to the nearest whole number.
@Impro: If you look at the sequence, it’s basically 7 * (1 + 2 + 3 + 4 + 5… 899), so you can reduce it to 7 times the numbers 1…899.
I came up with a similar equation when i was 17 (or so), i forget the details of how i came up with it, but the equation i used was:
a(a/2 + .5) = 1+2+3+…a
Nice, that’s another way to put it. And yep, they check out:
a(a/2 + 1/2) = a^2/2 + a/2 = a(a+1)/2
There must be an intuitive way to see that derivation also :).
I recently had a need to find the number of strokes in a series that went like this:
1+2+3+4+5+6+5+4+3+2+1
and found that the total is equal to the square of the middle number. So if the middle number is 10 then the grand total of them both up and down is 10^2 = 100
Thank u!!!
[…] recursion and calling a function within itself. Also what would make the solution even better is this - which is a mathematical formula that adds numbers from […]
kewl XD
Can anyone solve or write any algorithm for the follwing one.
Split the natural numbers in to two sets whose summation should be equal.
For example say number range from 1 to 10
can you split the number from 1 to 10 into two sets as follows whose sum is equal
Can anyone solve or write any algorithm for the follwing one.
Split the natural numbers in to two sets whose summation should be equal.
For example say number range from 1 to 10
can you split the number from 1 to 12 into two sets as follows whose sum is equal
1+5+9+4+8+12 = 39
2+6+10+3+7+11= 39
Can anyone derive formula for this. The above logic works only for the following condition else it will fail
Condition 1 : When n((n+1)/2) is Odd not application only applicable when the sum is even
Condition 2 : When the number needs to be split in to 2 sets have a increase uniformly or a series of number starting with 1.
Question 1 : Derive a formula for a number in the type series
Question 2 :Derive a formula for a number which is in random fashion say for example
1,50,24,25,3,2
Awaiting for the reply GUYS!!!