300, 299, 295, 286, 270, ?
Find the missing number in the following number series.

The correct answer is 245.

To find the missing number in the given series, let us analyze the pattern or difference between consecutive numbers:

$300-299=1=1^2$

$299-295=4=2^2$

$295-286=9=3^2$

$286-270=16=4^2$

The difference between consecutive terms is the square of consecutive natural numbers (1², 2², 3², 4², ...).

Following this pattern, the next difference must be:

$5^2=25$

Therefore, subtracting 25 from the last given number (270) gives the missing number:

$270-25=245$

Thus, the missing number in the series is 245.