Basic Mathematics

Finding the Missing Numbers in Inequalities

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Finding the Missing Numbers in Inequalities
Remember, inequalities are number sentences that use one of the following symbols called "inequality signs."

< means "is less than"
> means "is greater than"
≠ means "is not equal to"
≥ means "greater than or equal to"
≤ means "less than or equal to"
Here are some inequalities:

10 < 45
9 + 6 > 10
y − 1 ≥ 12
Finding the Missing Numbers in Inequalities
In this lesson, the problem asks you to find a number that will make the sentence true.

What number belongs in the box to make the inequality true?
4 + □ < 6
If the choices are 1, 2, 3, 4, and 5,
the only correct answer is 1
because 4 + 1 = 5 and 5 is less than 6.
Finding the Missing Numbers in Inequalities
Click on the number that belongs in the box.
□ < 5 − 3
4
8
2
3
1
Question 1 of 8
4 is not less than 5 − 3. 4 > 5 − 3 because 4 > 2. Try again.
8 is not less than 5 − 3. 8 > 5 − 3 because 8 > 2. Try again.
2 is not less than 5 − 3. 2 = 5 − 3 because 2 = 2. Try again.
3 is not less than 5 − 3. 3 > 5 − 3 because 3 > 2. Try again.
1 < 5 − 3 is a true sentence because 1 is less than 2.
First, simplify the expression on the right: 5 − 3 = 2
Finding the Missing Numbers in Inequalities
Click on the number that belongs in the box.
3 × 6 > □
19
34
21
14
24
Question 2 of 8
3 × 6 is not greater than 19.
3 × 6 < 19 because 18 < 19. Try again.
3 × 6 is not greater than 34.
3 × 6 < 34 because 18 < 34. Try again.
3 × 6 is not greater than 21.
3 × 6 < 21 because 18 < 21. Try again.
3 × 6 > 14 is a true sentence because 18 is greater than 14.
3 × 6 is not greater than 24.
3 × 6 < 24 because 18 < 24. Try again.
First, simplify the expression on the left: 3 × 6 = 18
Finding the Missing Numbers in Inequalities
Click on the number that belongs in the box.
7 × □ < 25
 5
18
 4
 7
 3
Question 3 of 8
7 × 5 is not less than 25.
7 × 5 > 25 because 35 > 25. Try again.
7 × 18 is not less than 25.
7 × 18 > 25 because 126 > 25. Try again.
7 × 4 is not less than 25.
7 × 4 > 25 because 28 > 25. Try again.
7 × 7 is not less than 25.
7 × 7 > 25 because 49 > 25. Try again.
7 × 3 < 25 is a true sentence because 21 is less than 25.
Multiply 7 times each number and see if the product is less than 25.
Finding the Missing Numbers in Inequalities
Click on the number that belongs in the box.
72 ÷ □ < 10
2
3
6
4
9
Question 4 of 8
72 ÷ 2 is not less than 10.
72 ÷ 2 > 10 because 36 > 10. Try again.
72 ÷ 3 is not less than 10.
72 ÷ 3 > 10 because 24 > 10. Try again.
72 ÷ 6 is not less than 10.
72 ÷ 6 > 10 because 12 > 10. Try again.
72 ÷ 4 is not less than 10.
72 ÷ 4 > 10 because 18 > 10. Try again.
72 ÷ 9 < 10 is a true sentence because 8 is less than 10.
Divide 72 by each number and see if the quotient is less than 10.
Finding the Missing Numbers in Inequalities
Click on the number that belongs in the box.
4 × 3 × 7 < 4 × 3 × □
2
5
8
6
4
Question 5 of 8
Since the first two factors are the same, compare just the third factors. 7 is not less than 2. Try again.
Since the first two factors are the same, compare just the third factors. 7 is not less than 5. Try again.
4 × 3 × 7 < 4 × 3 × 8 is a true sentence because 7 is less than 8.
Since the first two factors are the same, compare just the third factors. 7 is not less than 6. Try again.
Since the first two factors are the same, compare just the third factors. 7 is not less than 4. Try again.
The first two factors on each side of the inequality are the same. Compare the third factors.
Finding the Missing Numbers in Inequalities
Click on the number that belongs in the box.
5 + 9 + 11 > 5 + □ + 11
12
 8
 9
11
10
Question 6 of 8
Since two of the addends are the same, compare just the middle addends. 9 is not greater than 12. Try again.
5 + 9 + 11 > 5 + 8 + 11 is a true sentence because 9 is greater than 8.
Since two of the addends are the same, compare just the middle addends. 9 is not greater than 9. Try again.
Since two of the addends are the same, compare just the middle addends. 9 is not greater than 11. Try again.
Since two of the addends are the same, compare just the middle addends. 9 is not greater than 10. Try again.
The first and last addends on each side of the inequality are the same. Compare the middle addends.
Finding the Missing Numbers in Inequalities
Click on the number sentence that is true.
7 − 2 = 3 + 3
8 × 2 > 5 × 3
7 + 3 = 5 × 1
4 + 7 < 3 + 8
None of these
Question 7 of 8
7 − 2 is not equal to 3 + 3.
7 − 2 < 3 + 3 because 5 < 6. Try again.
8 × 2 > 5 × 3 is a true sentence because 16 is greater than 15.
7 + 3 is not equal to 5 × 1.
7 + 3 > 5 × 1 because 10 > 5. Try again.
4 + 7 is not less than 3 + 8.
4 + 7 = 3 + 8 because 11 = 11. Try again.
One of these is a true number sentence. Try again.
Simplify the expressions on each side of the equation or inequality. Then compare the results.
Finding the Missing Numbers in Inequalities
Click on the number sentence that is true.
24 + 8 > 4 × 9
3 × 7 > 40 ÷ 2
5 + 4 = 63 ÷ 9
19 − 5 < 3 × 4
None of these
Question 8 of 8
24 + 8 is not greater than 4 × 9.
24 + 8 < 4 × 9 because 32 < 36. Try again.
3 × 7 > 40 ÷ 2 is a true sentence because 21 is greater than 20.
5 + 4 is not equal to 63 ÷ 9.
5 + 4 > 63 ÷ 9 because 9 > 7. Try again.
19 − 5 is not less than 3 × 4.
19 − 5 > 3 × 4 because 14 > 12. Try again.
One of these is a true number sentence. Try again.
Simplify the expressions on each side of the equation or inequality. Then compare the results.
Finding the Missing Numbers in Inequalities