What should the next number be? 100 96 104 88 120 56

100 - --> 96 is - 4

96 - --> 104 is + 8

104 - --> 88 is - 16

88 - --> 120 is + 32

120 - --> 56 is - 64

So first we go down by 4, then up by 8, then down 16, then up 32, then finally down 64.

The pattern of numbers is: - 4, + 8, - 16, + 32, - 64

Notice it's the powers of 2:

2^2 = 4

2^3 = 8

2^4 = 16

2^5 = 32

2^6 = 64

each term doubles. Also each term alternates in sign. One is positive, then the next is negative and so on.

The last difference is - 64, which doubles to - 128. Change the sign to positive to get + 128

Add 128 to the last term of 56 to get

128+56 = 184

Therefore, the final answer is 184