58
Approximate equality
Textbook: Part 2, lesson 58, pp. 60–62
GoalApproximate equality: the ≈ sign.
New words
approximate equality · taqribiy tenglikclose number · yaqin son≈ sign · ≈ belgisiround number · yumaloq son
Explanation
Approximate equality is written with the ≈ sign and read “is about equal to”. 1 998 ≈ 2 000 and 31 ≈ 30. When choosing a close round number the difference from the exact value must be small: 7 982 ≈ 8 000 with difference 8 000 − 7 982 = 18. 4 997 ≈ 5 000 with difference 3.
Worked examples
4 997 ≈ 5 000; the difference is 5 000 − 4 997 = 3.
598 ≈ 600; the difference is 2.
Class activity
“Which is closest?”: the teacher says a number and children write the closest round number with the ≈ sign.
Practice
1
49 ≈ ? (the closest ten)
50
2
Which hundred is closest to 598?
600
3
4 997 ≈ 5 000. What is the difference between the exact and approximate values?
3
4
7 982 ≈ 8 000. What is the difference?
18