Greg is building a fence. He places two sections end to end. One section measures $3$ meters, and the other measures $120$ centimeters.

1. Greg thinks the fence will be $123$ units long but is not sure what the units are. His sister Elisa thinks he is wrong. What do you think? Explain.

   Answer (a):

   Elisa is right. Do you know why?

2. Find at least two ways to express the length of the fence.

   Hint (b):

   Try writing the length in meters and centimeters.