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ACTIVITY 5
ADDITION AND SUBTRACTION OF WHOLE NUMBERS
1. Give an example of a physical model that provides an intuitive understanding of the
operation of addition
2. In mathematics, the word ‘or’ is the ‘inclusive or’ meaning ‘one or the other or
both’.
Example: If we say that the element x belongs to the set A or the set B, we mean
that either x  A , or x  B , or x  both A and B . Construct a sentence to include
the word ‘or’ exclusively.
3. Construct two sets (A and B) which have some common elements.
a) Find the union of the two sets ( A  B ).
b) Find the intersection of the two sets ( A  B ). Use a Venn diagram to represent the
intersection.
4. Construct two ‘disjoint’ sets.
5. Use the disjoint sets in Problem 4 to explain the operation of addition of whole
numbers.
6. Give examples to illustrate the following basic properties of whole numbers:
a) Closure
b) Identity
c) Commutative
d) Associative
7. Give an example of a physical model that provides an intuitive understanding of the
operation of subtraction.
8. What is meant by the following terms:
a) addend
b) minuend
c) subtrahend
d) difference
9. Solve exercise # 28, page 87 (Find two addition problems and two subtraction
problems. At least one of the subtraction problems should represent comparing sets).
10. Does a whole number c = a – b exist for every pair of whole numbers a and b.
11. Do the properties of addition of whole numbers hold for subtraction. Give examples
to justify your answers.
12. Solve exercises 15 and 17 (Page 86).