Question

What is the sum of the first 13 terms in the Fibonacci Sequence?





Term


1


2


3


4


5


6


7


8


9




Fibonacci Number


1


1


2


3


5


8


13


21


34

Answer 1

Could you write the first 13 terms and then add them up?

Answer 2

one way of doing this is to just work out the 1st 13 terms and then just add them up.

Answer 3

You already have 9 of them in your post.

Answer 4

you have been given the 1st 9 terms above.

Answer 5

Thats a confusing question I think. Some people start this sequence with 0 and some start it with 1.

Answer 6

@Mertsj - we seem to be experiencing ESP here ;-)

Answer 7

i get 609

Answer 8

12 is 144 and 13 is 233

Answer 9

but i cheated
http://www.wolframalpha.com/input/?i=sum+n+%3D+1to+13+fibonnaci

Answer 10

thank u satellite

Answer 11

how did u fined that site

Answer 12

that site is popular

Answer 13

Lets find the sum of the first 100 Fibonacci numbers.

Answer 14

@sunsetlove - I would still advise you to try and work this out yourself so that you understand it better. do you know how the Fib series is constructed?

Answer 15

no i dont

Answer 16

1
1
1+1=2
1+2=3
2+3=5
3+5=8
5+8=13
8+13=21
13+21=34

Answer 17

so you have the first two terms as 1, 1
the next one is the sum of these two terms, so 1+1=2
now we have 1, 1, 2
next term is sum of last two terms, so 1+2=3
now we have 1, 1, 2, 3
next term is sum of last two terms, so 2+3=5
now we have 1, 1, 2, 3, 5
etc

Answer 18

i tryed that it confused me so 21+36 is next right ?

Answer 19

21+34

Answer 20

the last two terms in the sequence given to you are 21 and 34, so next term will be the sum of these last two terms:
21+34=55

Answer 21

so 10th term is 55
which means 11th term is 55+34=89

Answer 22

do you see the pattern now?

Answer 23

and the 11th is 34+89=123 right

Answer 24

remember, to get the next term, you add the previous two terms
so we know:
10th term is 55
11th term is 89

so 12th term = 55+89=144

Answer 25

owww
ok i get it

Answer 26

good - you are in a much stronger position now - mathematically speaking ;-)

Answer 27

\[f_n=f_{n-1}+f_{n-2} , n >2 ,f_1 =1 ,f_2=1\]

Answer 28

this pattern of numbers is actually quite interesting as it arises a lot in nature - you may wish to investigate if you are interested...

Answer 29

so 13 would be 89+=233

Answer 30

yup

Answer 31

im anser would be 233 ?

Answer 32

no - you need to add up all the values in the series.

Answer 33

up to the 13th one

Answer 34

ok

Answer 35

so sum=1+1+2+3+5+8+...+89+233

Answer 36

1+1+2+3+5+8+13+21+34+55+89+144+233=609 and that is the sum of the first 13 terms of the sequence