MATH 140 InClass Exercise on Bases and Manipulatives

1. For the first twenty-five minutes of class, design a lesson on subtraction of three digit numbers using the base ten blocks. This should be an outline of what you need to cover in such a lesson. First, assume that the students have not seen these manipulatives before your lesson. Then show how subtraction proceeds using 213-184.

2. In each of the following perform the given operation in the given base. then check your answer in the given base. For example in a subtraction problem check the answer by addition. then check the answer a second way by changing all the parts of the problem to base ten and performing the operation there.

a) 20031₅ – 22142₅ =

b) 5568₁₂ ¸ 2T₁₂ =

c) 1244₅ ¸ 33₅ =