N3D9TNp16

Answer to Problem 16:

Low estimate:; high estimate:  .  I rounded both numbers down to get a low estimate and I rounded both numbers up to get a high estimate.

This problem might be changed to have students provide and estimate, then explain how their estimate would compare to the exact product.  If students have experienced strategies for composing and decomposing in earlier grades they may be able to calculate the value almost as quickly as the estimate was generated.  Teachers should be aware of how changes in instruction at the earlier grades may impact these situations and problems.