Final answer:
The length of the object can be estimated to be 2.5 cm, with the tenths digit being uncertain. The top ruler with millimeter markings allows for more precise measurements, but the hundredths digit is still uncertain.
Step-by-step explanation:
The length of the object can be estimated to be 2.5 cm. The bottom ruler does not have millimeter markings, so the tenths digit can only be estimated. Another person may estimate it as 2.4 cm or 2.6 cm. The top ruler with millimeter markings allows for more precise measurements, such as 2.55 cm, but the hundredths digit is still uncertain.