6. A pencil measures 8 cm long. What is this length in mm?
Answer: A
80 mm
To convert centimeters to millimeters, one must multiply the length in centimeters by 10. Therefore, an 8 cm pencil is equivalent to 80 mm.
A) 80 mm
This option is correct because the conversion from centimeters to millimeters involves multiplying by 10. Thus, 8 cm x 10 = 80 mm.
B) 800 mm
This option is incorrect as it represents a value that is ten times larger than the actual conversion. The correct conversion from 8 cm to mm is 80 mm, not 800 mm.
C) 8 mm
This option is also incorrect because it suggests a misunderstanding of the conversion factor. 8 mm would be the equivalent of 0.8 cm, not 8 cm.
D) 0.8 mm
This option is incorrect, as it significantly underestimates the conversion from centimeters to millimeters. The value of 0.8 mm would correspond to 0.08 cm, which is not relevant here.
Conclusion
In summary, 80 mm is the correct conversion of 8 cm, as it accurately reflects the multiplication by 10 needed for the conversion. All other options fail to provide the correct value either by overestimating or underestimating the length in millimeters. Therefore, A is the only valid answer.