Positive and Negative Integers
Primary 4 · Mathematics
Positive and Negative Integers
Lesson 1 of 4
25 min
Let's begin
On a cold night near the top of Mount Karisimbi, a guide reads his thermometer. It says 3 degrees below zero. How can a number be less than nothing? In this lesson you will meet numbers that are smaller than zero.
Positive numbers are greater than 0: 1, 2, 3 … We can write them with a plus sign, +3, or without it, 3.
Negative numbers are less than 0. We always write them with a minus sign: −1, −2, −3 … We read −3 as "negative three" or "minus three".
Zero is neither positive nor negative. The whole numbers, their negatives and zero together are called integers.
The meaning of a negative number depends on what zero means in the story.
The Musanze thermometer shows 6 °C: six degrees above zero. The Karisimbi thermometer shows −3 °C: three degrees below zero.
Tip
Above or below? Find zero first. Above zero, or more than nothing, is positive (+). Below zero, or owing, is negative (−).
Work each one in your exercise book first. Then tap Show answer to check.
Write an integer for: 8 degrees below zero.
Answer: −8
Write an integer for: a profit of 1 200 Frw.
Answer: +1 200 (or 1 200)
A lift stops at the third floor under the ground. Write the floor number as an integer.
Answer: −3
Is 0 positive or negative?
Answer: Neither. Zero is the only integer that is neither positive nor negative.
Mutesi owes 500 Frw. Then she earns 2 000 Frw and pays back what she owes. How much money does she have now?
Answer: 1 500 Frw, because 2 000 − 500 = 1 500.
What you learned today
Sources and credits
The stories, Rwandan worked examples, diagrams and practice questions were written by Ganzaa.
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