@thegreat5664
People who passed 10th grade getting excited as they remember APs:
@AvaL3239
Just use this when u see 1+2+3+•••+n 1/2 × n × (n+1)
@jasonfyk
for those who want to understand a little more about the forms in chat: since this type of number is basically a bunch of simple sums, you don't need to worry about sign complexities. a = first number b = last number c = quantities of numbers to be added example 1: 1+2+3+4 a=1 b=4 c=4 example 2: 25+26+27+28+29 a=25 b=29 c=5 (25, 26, 27, 28 and 29 are 5 different numbers so c=5) basically the equation goes like this: c*((b/2)+(a/2)) equation for example 1: 4*((4/2)+(1/2)) equation for example 2: 5*((29/2)+(25/2)) other ways of writing this equation formula: c*((b/2)+(a/2)) c*((b*.05)+(a*0.5)) c*((b+a)/2) c*((b+a)*0.5) c/2*(b+a) c*0.5*(b+a) (c*(b+a))/2 (c*(b+a))*0.5 ((c*b)/2)+((c*a)/2) ((c*b))*0.5)+((c*a))*0.5) ((c*b)+(c*a))/2 ((c*b)+(c*a))*0.5 and the list continues with several other ways of writing the same equationary formula..
@KaylaRicco_
If I was in that situation I’d start adding it one by one 💀💀 Edit: This comment was supposed to be taken with a sense of humour so don’t take it seriously like some folks
@AzaabcG
There is a official formula called ‘Gauss’s method’ which he officially discovered at age of 8. In which he says’If sequence is being added by constant numbers(arithmetic progression),then’ Add First and Last members of sequence and divide product by two, therefore multiply it by number of how many members are there’ Substantiation: 1+50=51 51/2=25.5 25.5*50=1275
@hdgenius5182
This is known as arithmetic progression the formula is sn = n/2(a+l)
@fransabram34
Arithmetic series : Sn=n/2(a+L) a= first term L= last term n = no. Off terms . Only when you know last term though. Otherwise use : sn= n/2 ( 2a+ (n-1)d)) a - first term d - first common difference ( T2-T1/ T3-T2/ T4-T3........)
@z34rk79
"Ok so pull out my calculator, 1+2+3+4+5......"
@Jay1717_
The actual formula is "Sn= n/2[2a+(n-1)d]" n is the number i.e 50, a is 1st term i.e 1, d is common difference i.e 1. 50/2[2(1)+(50-1)1] 25[2+49] 25x51 1275 This is actually from a algebra topic called "Arathemic Progression"
@ayanokoujikiyotaka1942
Gauss left the chat
@TickleBot32
: 50 Sigma ( r ) = (1/2)(50)(51) = 1275 r = 1 Using standard summation formulae (1/2)n(n+1)
@KofisKitty
Easier format is n • (n+1) /2 n= last number of enumaration 50 • 51= 2550 2550 /2= 1275
@Eden07211
Me who studied arithmetic progression in 9th Grade : "I'm Speed" Edit: omg how did i got so many likes!!!
@leoofficial527
"it's not 1000, it can't be that ez" "915 too little, seems odd" "Last one not divisible by 5" Picks C
@asparkdeity8717
Proof of general formula: S = 1+2+….+k S = k+(k-1)+…+1 Add them together; 2S = (k+1) + (k+1) + … + (k+1) [k times] 2S = k(k+1) S = k(k+1) / 2 Can generalise this for any arithmetic progression of the form Un = a+(n-1)d. This gives: Sn = n/2 [2a + (n-1)d]. The above is a special case with a = 1, d = 1, n = k
@hitesh1941
A more easy way . . Look at the last digit ( in this case 50) 1,2,3,.......,50 Let 50=x *Get x/2 50÷2= 25 *multiply x/2 with x 50×25=1250 *add x/2 to the no. obtained 1250+25=1275 Hope it will prove helpful 🙂
@kanishkgamer4556
we can also use n(n+1)/2
@Muslim-Revert
Just do AP Sum if n terms of ap = n/2( 1st term + last term). Here n =50, 1st term=1, last=50 50/2(1+50) 25×51 Get a paper and calculate 1275.
@gtmrox9405
I think my brain just went through a mental breakdown
@WillEnj0y