We the Travellers — II
Class 5 · Mathematics
5 ideas in Class 5 Mathematics, explained in plain words, with games and quizzes to practise.
Addition and Subtraction are Linked
Part of: Addition and subtraction go together
Addition and subtraction undo each other. If 30 + 20 = 50, then 50 − 20 = 30 and 50 − 30 = 20. So a subtraction answer can be checked by adding it back to the number that was taken away.
Why it matters. Children who see this link can check their own work and spot mistakes without asking an adult.
Try it in two minutes
- Put 12 beans in one pile and 7 in another. Say: 12 + 7 = 19.
- Take the 7 beans away from the 19. Ask: what is left, and which sentence does that match?
- Ask your child to write the other two sentences that use 7, 12 and 19.
Try at home. Ask your child to do any subtraction from their notebook and check it by adding.
Adding Large Numbers
Part of: Working with large numbers
Large numbers are added in the same way as small ones. Line up ones under ones, tens under tens and so on, add each column from the right, and carry when a column makes 10 or more. Example: 2436 + 1352 = 3788.
Why it matters. Adding large amounts of money, distances or counts is part of daily life, and untidy columns are the most common source of mistakes.
Try it in two minutes
- Write 3465 and 2759 on paper, one below the other, with ones lined up.
- Ask your child to add the ones column and say what to carry.
- Continue column by column and ask them to explain each carry.
Try at home. Ask your child to add the prices of two items from a shop leaflet or bill.
Subtracting Large Numbers
Part of: Working with large numbers
We subtract column by column from the right. If the top digit is smaller than the bottom digit, we regroup: take 1 from the next place and turn it into 10 in this place. Always check by adding the answer to the smaller number.
Why it matters. Finding how much is left or how much more is needed is a skill children use with money, distance and time.
Try it in two minutes
- Write 6000 − 2345 in columns.
- Ask your child why we cannot take 5 from 0 and how to regroup.
- Check together: does the answer plus 2345 give 6000?
Try at home. Ask your child how much money is left when a small amount is spent from a bigger one, then check the answer by adding.
Quick Sums and Differences
Part of: Quick methods and patterns
Some numbers are easy to work with: 10, 100 and 1000. To add 99, add 100 and take away 1. To subtract 9, subtract 10 and add 1 back. To find what to add to 45 to reach 100, find 45 + 54 = 99 and add one more.
Why it matters. Quick methods build number sense and make mental calculation faster and more fun.
Try it in two minutes
- Ask: 58 + 99. Show how it is 58 + 100 − 1.
- Ask your child to try 83 − 9 using 83 − 10 + 1.
- Ask: which number added to 72 makes 100?
Try at home. Ask your child to find how much change they would get from ₹100 for small purchases.
Sums of Consecutive Numbers
Part of: Quick methods and patterns
Consecutive numbers follow one another with no gaps, like 8, 9, 10. Three or five consecutive numbers add up to that many times the middle number. For example 8 + 9 + 10 = 3 × 9 = 27.
Why it matters. Spotting patterns lets children replace long adding with quick reasoning and shows that mathematics has hidden order.
Try it in two minutes
- Write 4 + 5 + 6 and 5 + 6 + 7. Ask: what is the middle number each time?
- Check that each sum is 3 times the middle number.
- Ask your child to find 11 + 12 + 13 without adding.
Try at home. Ask your child to find any three consecutive numbers that add to 45.
What your child will practise
- Adding Large Numbers: Ocean Quick Fire (Quick Fire)
- Addition and Subtraction are Linked: Space Quest (Flip and Match)
- Quick Sums and Differences: Space Quest (Match It Up)
- Subtracting Large Numbers: Ocean Puzzle (Clue Puzzle)
- Sums of Consecutive Numbers: Number Quest (Collect the Answer)
- Quiz: Adding Large Numbers (8 questions)
- Quiz: Addition and Subtraction are Linked (8 questions)
- Quiz: Quick Sums and Differences (8 questions)
- Quiz: Subtracting Large Numbers (8 questions)