Question

about 3 cm shorter than 9 cm between 9 and 18 cm longer than 18 cm

Explanation:

Step1: Estimate number of paper - clip lengths

Count that the length of the blue object is about 3 times the length of the paper - clip.

Step2: Calculate approximate length

Since the paper - clip is about 3 cm long, the length of the blue object is $3\times3 = 9$ cm. So it is shorter than 9 cm considering possible measurement errors.

Answer:

Shorter than 9 cm