What does it mean?
The equals sign means “has the same value as”. It is not an instruction to put an answer after it. Both 48 + 12 = 60 and 60 = 48 + 12 are true. In 46 + 18 = 50 + □, the box must make the entire right side equal the entire left side.
The equals sign says the value on the left is the same as the value on the right. A missing value must make that relationship true.
Learning goal: Solve open addition and subtraction equations and explain equality as two expressions with the same value. The grade is a suggested starting point; school sequences vary. Use the first worked example to check readiness, and Pre-algebra if an earlier idea needs revisiting.
See the idea
Read each diagram with its labels, then follow the worked examples. Practice questions include their own measurements and information.
Enlarge diagram to read the labels
Swipe across the enlarged diagram to read every label.
Enlarge diagram to read the labels
Swipe across the enlarged diagram to read every label.
Choose a method and explain why it works
Find the value of a complete known side, then decide what the unknown side needs. Alternatively, use balance: when one addend increases by one, the other can decrease by one to keep the total unchanged. Always replace the box with your answer and calculate both sides as a final check.
Key rule and when to use it
The equals sign means both sides have the same value. Find a missing number by keeping that balance, not by continuing a chain of instructions.
Worked examples, step by step
Example 1: Solve 46 + 18 = 50 + __.
- 46 + 18 = 64.
- The right side must also equal 64.
- 50 + 14 = 64.
- The missing value is 14.
Answer: 14
Example 2: Decide whether 39 + 26 = 40 + 25.
- 39 + 26 = 65.
- 40 + 25 = 65.
- Both sides have the same value.
- The equation is true.
Answer: true
Example 3: Complete 87 + 26 = 90 + □.
- The left side equals 113.
- The right side needs 113 − 90 = 23 in the box.
- Check: 87 + 26 = 113 and 90 + 23 = 113. Moving 3 from 26 to 87 preserves the sum.
Common mistakes and important boundaries
Do not fill the box with the answer to just the first calculation. In 34 + 16 = 50 + □, the box is zero, because 50 + 0 equals 50. Writing 50 in the box makes the right side 100. Read every operation on both sides of the sign.
A point to explain
The learner may read “=” as “now write the answer” and ignore the full expression on the right.
Compare an uncertain attempt with the closest worked example. Look at the meaning of each operation, unit and label before repeating the arithmetic.
Missing Number Equations and the Equals Sign — practice
Work on paper first. Open each answer afterwards and compare the reasoning. Print the questions with or without the separate answer key; no account is required.
Name: ____________________ Date: __________
Which statement is true?
Show answer
36 + 14 = 40 + 10
What does the equals sign mean in 27 + 18 = 30 + 15?
Show answer
Both sides have the same value.
48 + __ = 83
Show answer
35
72 - __ = 29
Show answer
43
46 + 18 = 50 + __
Show answer
14
Why can 39 + 26 = 40 + 25 be true even though the addends are different?
Show answer
Both sides have total value 65.
A learner says 34 + 16 = 50 + 5 because 34 + 16 = 50. Is the equation true?
Show answer
no
Fill the blank to keep equality true: 125 + 75 = 160 + __.
Show answer
40
Missing Number Equations and the Equals Sign — answer key
36 + 14 = 40 + 10
Both sides have the same value.
35
43
14
Both sides have total value 65.
no
40
Questions students and parents ask
Can an equation have calculations on both sides?
Yes. 30 + 12 = 40 + 2 is true because both sides equal 42. An equals sign does not require a single numeral immediately after it.
Can a missing number be zero?
Yes. Zero may be exactly what preserves equality. Decide from the values on both sides rather than assuming a blank must contain a positive number.
Is this a complete set of textbook exercise solutions?
No. This guide adapts BananaLearn’s own teaching examples and practice. It is not official NCERT material or a promise of the exact chapter sequence in a particular board, country or textbook edition.
What if the examples are still difficult?
Revisit Pre-algebra. Try the first example with its model, then attempt one fresh question independently. A correct copied answer is not evidence that the method can be used without support.
Help at home
Read equations aloud using “has the same value as”. Include true equations with the single number on the left to challenge an answer-only reading.
Keep one example of the learner’s own working. A repeated difficulty across fresh questions can guide a discussion with their teacher; one short practice sheet does not establish a diagnosis or a full mastery profile.
Connect this idea to the next skill
About this guide
Based on BananaLearn’s Grade 3 course lesson “Open Equations and Equality”. The explanations have been adapted for independent reading; course diagrams are reused where they fit the idea, and missing classroom givens are made explicit in questions.
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