Final answer:
The smallest sized imperial spanner to fit can be found by converting the object's mm measurement to inches, and then selecting the next largest standard imperial spanner size.
Step-by-step explanation:
To determine the smallest sized imperial spanner that will definitely fit, we must convert from millimeters to inches since spanners are typically sized in either metric or imperial units. One inch equals 25.4 millimeters, which is a standard conversion used in measurement. For small objects such as a crayon or pencil, measuring in inches is appropriate since these objects do not span large distances, just like the crayon example provided. With this in mind, if the object to fit the spanner has a size precisely known in mm, you will then convert that size to inches to find the closest, but not smaller spanner size available. For instance, if a bolt is 13mm across, converting to inches gives approximately 0.511811 inches, which means a 1/2 inch spanner is slightly too small, so the next size up, typically a 9/16 inch spanner, would be the smallest size that definitely fits.