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Calculating with Rational Numbers

Objective

In this lesson we will review positive and negative integers.

Previously Covered:

In the sections above, we discussed prime numbers and the fact that they have exactly two factors: the number one and the number itself.
We also covered the divisibility rules (shortcuts to tell you if one number is divisible by another number) and the idea of prime factorization, which is the process that finds the prime-number products of a given composite number.

Those Pesky Negative Numbers

We know, we know: This is why calculators were invented. But let’s stay positive—so to speak.

We’ll start with integers, rather than fractions and decimals, because the rules are all the same, and integers are easier to add, subtract, multiply, and divide mentally.

Test yourself:

Question

Solve x = –19 + 41.

x = –60
x = –60
x = 22
x = 60

Reveal Answer

The correct answer is C. Find the difference between 41 and 19, since the numbers have opposite signs. The difference is 22. The larger absolute value is 41, so the answer is positive.

Review

If unclear about operations for integers, go back and review the specifics on how to add, subtract, multiply, and divide integers.
Remember to have a common denominator when you are adding and subtracting fractions and mixed numbers.

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