Number-Pair Bridge
A missing addend is the gap between the known part and the total. Useful number pairs support mental addition and subtraction.
Before you try
Before you play, make a prediction: 65 + __ = 100 Explain what you expect and what part of the model will help you check it.
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Interactive activity
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What happened?
Move a control to see what changes and why.
The game practises one idea at a time with simple drawn pictures. Check the same idea with real objects and your NCERT textbook (Chapter 7: The Cleanest Village, pages 95–114).
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Try these ideas
- Join a number to its partner so the pair reaches the bridge target.
- Try a new puzzle with ↻. Describe what changed and which mathematical rule stayed the same.
- Complete a round, then explain your method before you move to the next one.
Why it works
A missing addend is the gap between the known part and the total. Useful number pairs support mental addition and subtraction.
375 + 625 = 1000. Subtracting 375 from 1000 finds the missing partner. Join a number to its partner so the pair reaches the bridge target.
Check the pair by adding it back to the target total.
This activity connects to The Cleanest Village, NCERT Class 4 maths, printed pages 95–114. Use the picture or objects to explain each step before relying on a calculation. The game practises one part of the chapter at a time; the other three activities extend the chapter’s ideas.
Worked example: Find the missing partner in 460 + __ = 1000. Count from 460 to 500: 40. From 500 to 1000: 500. The missing part is 40 + 500 = 540.
Check your understanding
Question 1 of 2
65 + __ = 100
An estimate of 298 + 203 is closest to…
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
For parents & teachers
- Try with everyday materials. Join a number to its partner so the pair reaches the bridge target. Ask the child to make a new example using paper, counters, household objects or a labelled sketch.
- Listen to the explanation. Check the pair by adding it back to the target total. Ask “How could we check?” and encourage a second representation of the same idea.