What does the 'number' sizing for twist drills range from?

The correct answer is based on the established numbering system for twist drill sizes. In the drill sizing chart, the number size ranges from No. 1 down to No. 80, with No. 1 being the largest size and No. 80 the smallest. Each increase in number indicates a decrease in size, and twist drills within this range are commonly used in aviation maintenance and other precision drilling applications.

Choosing No. 80 as the smallest size in the range emphasizes the standardization used across different industries, ensuring that mechanics and engineers have a common understanding of drill sizes. Understanding this numbering system is crucial for selecting the appropriate drill bit for various tasks, especially in aviation, where precision is essential.

The other options do not accurately reflect the established sizing range for twist drills, as they either extend beyond the standard sizes (as with options that include sizes not typically used) or miss important sizes within the recognized range.