Select the most reasonable metric unit for the given object.
A soccer field is about 100 ___ long.

Perform the indicated operation.

$310mm-6cm$

Perform the indicated operation.

$2.4m\times 6$

Perform the indicated operation.

Select the most reasonable metric unit for the given object.

A pencil is about 18 ___ long.

Select the most reasonable metric unit for the given object.

A grain of rice is about 7 ___ long.

Fill in the blank to convert as indicated. 

4500 mm = _____ m

Fill in the blank to convert as indicated. 

650 m = ______ dam

Fill in the blank to convert as indicated. 

7300 cm = ________ mm