Complete the series by filling the appropriate number.

Logic: In the given figures, upper number is sum of the square of the lower numbers.

In the first figure,

 ⇒( 2)² + (4)² = 4 + 16 = 20

In the second figure,

⇒ (3)² + (9)² = 9 + 81 = 90

Similarly, In the third figure,

 ⇒ (2)² + (3)² = 4 + 9 = 13

Hence, the missing term in the series is "13".