Question

IQ test -- What is the next number in sequence 7, 2 , 0, 7, 8 , 4 , 3, ?

Answer 1

One way to solve this is : 

Assume the sequence as 7,2,0,7,8,4,3,x

Now, observe the difference between 1st and 5th term, 2nd and 6th, 3rd and 7th, and 4th and 8th. 

1st and 5th
7-8 = -1

2nd and 6th
2-4 = -2

3rd and 7th
0-3 = -3

Thus, 4th and 8th should be -4. 
7-x = -4
-x = -4 + -7
-x = -11
x = 11

Thus, answer is 11. 

Answer 2

Let us assume next number to be x
now the sequence looks as;
7,2,0,7,8,4,3,x

now divide the number into 2 groups;
it will look like;
(7,2,0,7) and (8,4,3,x)
now in the first group add first 3 terms and subtract the second term from it. This will give us the fourth term
7+2+0=9
9-2=7
similarly, in the second group add first  terms 
8+4+3=15
now subtract the second term
15-4=x
x=11
Answer: The next term is 11