Question

The difference between the number of purchases at an art gallery during one month and the number of purchases during the next month must be an integer. Which statement must also be true of this number?

A It is also a whole number.

B It is also a natural number.

C It is also a rational number.

D It is also an irrational number.

Answer 1

Natural numbers: {1, 2, 3, 4, ....}
Whole numbers: {0, 1, 2, 3, ....}
Rational Numbers: [any number that can be written as a fraction]
Irrational numbers: [decimal numbers that cannot be written as a fraction]
Integers: {... -3, -2, -1, 0, 1, 2, 3, ...}

If they sold more pieces the following month the answer would be a whole or natural number.

If they sold the same number of pieces the following month the answer would be zero; a whole number.

If they sold fewer pieces the following month the answer would be a negative number; an Integer.