Identify the single term that does not conform to the pattern in the following number series:

11, 75, 11, 136, 87, 303, 268

The correct option is 268.

To identify the term that does not conform to the pattern, let us analyze the relationships and differences between consecutive terms in the given number series:
11, 75, 11, 136, 87, 303, 268

Let us compute the differences between successive numbers:

1st step (11 to 75):
$75-11=+64=+4^3$

2nd step (75 to 11):
$11-75=-64=-8^2$

3rd step (11 to 136):
$136-11=+125=+5^3$

4th step (136 to 87):
$87-136=-49=-7^2$

5th step (87 to 303):
$303-87=+216=+6^3$

Observe the alternating pattern of operations:
+4³, -8², +5³, -7², +6³, -6²

Following this rule, the next operation after adding 6³ should be subtracting 6² (which is 36):

6th step:
$303-6^2=303-36=267$

However, the given term in the series is 268 instead of 267.

Therefore, 268 is the incorrect term that does not fit the pattern.