SUM the numbers if you can.

Enter The total from 1 to the number given: example sum 1 to 5 = 15
Add up from 1 to the number given inclusive:
E.g. Sum of all numbers from 1 to 5 = 15 (1 + 2 + 3 + 4 + 5)
A mental arithmatic test for jetpunkers.
For those that read the instructions: n x 1/2n + 1/2n = the total sum from 1.
Quiz by Malbaby
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Last updated: December 5, 2017
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First submittedDecember 5, 2017
Times taken67
Average score65.0%
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Hint
Answer
8
36
44
990
16
136
100
5050
38
741
6
21
21
231
88
3916
25
325
11
66
32
528
7
28
50
1275
14
105
9
45
40
820
22
253
18
171
70
2485
24
300
+1
Level 22
Jul 14, 2018
Dominated this quiz with 1/20! lol
+1
Level 71
Jul 14, 2018
Plenty of room for improvement then!
+1
Level 73
Jul 18, 2018
This is an amazing quiz and a real challenge
+1
Level 73
Jul 18, 2018
Another trick is n*(n+1)/2 also gives you the sum of all the numbers from 1. e.g. for 8 do 8*9/2
+1
Level 56
Sep 4, 2022
that's what I did too
+1
Level 51
Oct 16, 2022
([X/2]+0.5)*X

E.G. ([8/2]+0.5)*8