It is possible to find a polynomial of order 7 that will fit the given numbers and any other number. Other functions are also possible.
The following polynomial, of order 6, fits them:
Un = (-5n6 + 114n5 - 1020n4 + 4540n3 - 10465n2 + 11696n - 4800)/60 for n = 1, 2, 3, etc.
With this rule, the next number is -160.
However, the answer that is most likely being sought is that the numbers in odd position are the counting numbers and the ones in even positions are their squares. With that rule, the next number would be 16.
Technically, any of these answers is correct. But you will only get marks for the last answer unless your teacher is a true mathematician.
1+1=2 : 1+2=3 : 2+3=5 : 3+5=8Therefore the next number is 8
456789
21
12110 0r 1210
3,5,8,13 is followed by 21. 1,1,2,3,5,8,13,21,34,55,... is the Fibonacci series or Fibonacci sequence where the next number in the sequence is the sum of the last two numbers (1+1=2, 1+2=3, 2+3=5, etc.)
1+1=2 : 1+2=3 : 2+3=5 : 3+5=8Therefore the next number is 8
The next number is 4, followed by -2
8 -1 then +3
The next number in the sequence is 18. It's +1, +2, +3, +4, ....
4
456789
You add two then take one. 1+2=3, 3-1=2, 2+2=4, 4-1=3. The next number is 5.
Zero
Sequence is +4 - 3 + 5 - 2 + 6 - 1 (+1 - 1)2 6 3 8 6 12 next number 11
13, 21 - it is the Fibonacci sequence
21
12110 0r 1210