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CBSE Class 1 · Mathematics

How Many? (Addition and Subtraction of Single Digit Numbers)

Official NCERT chapter from Joyful Mathematics (English) (book code aejm1). ExamMaster notes are original teaching at CBSE Class 1 depth.

This lesson follows the official chapter “How Many? (Addition and Subtraction of Single Digit Numbers)” in Joyful Mathematics (English). The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 1
  • Easy level
  • 8 concepts

1People joining a park is an addition story

People who join the park add to the group you already counted. The story is a join, not a take-away.

Write the plus mark only after you can say “they joined”.

Figure. People who join add to the group you already counted. Already 8 and join 5 make 13 now.

How it works

  1. Count who are thereThe start group.
  2. Count who joinThe new group.
  3. Join the two countsThat sum is how many now.

2People leaving is a take-away story

People who leave are a counted part taken out. The story is take-away, not a join.

Write the minus mark only after you can say “they left”.

Figure. People who leave are a counted part taken out. Start 9, leave 4, remain 5.

How it works

  1. Count who are thereThe start group.
  2. Count who leaveThe part that goes.
  3. Name what remainsThat is the new count.

3Join two single-digit groups

8 and 5 join to 13 only after both groups have been counted. The plus mark is shorthand for that join.

Count on from the larger group if you like. Do not invent a third group.

Figure. 8 and 5 join to 13 only after both groups have been counted. The plus mark is shorthand for that join.

How it works

  1. Count group AFinished count.
  2. Count group BFinished count.
  3. JoinSay the new last word.

Join 8 and 5

A park has 8 children. 5 more join. How many now?

  • Start8
  • Join 58 + 5
  • Count on13

Pro tip. Count on from the larger group.

4Take away a single-digit part

9 take away 4 is 5 when four counted people actually leave. The minus mark waits for that leaving.

Joining the 4 back must rebuild 9. That is the check.

Figure. 9 take away 4 is 5 when four counted people actually leave. Joining 5 and 4 must rebuild 9.

How it works

  1. Start at 9A finished count.
  2. Take 4Point at the leavers.
  3. Remain 5Check: 5 + 4 = 9.

Take 4 from 9

9 children in the park. 4 leave. How many remain?

  • Start9
  • Take 49 - 4
  • Remain5

Pro tip. Join back to check.

5Count on from the larger group

To join 8 and 5, hold 8 and count five more words: 9, 10, 11, 12, 13. That is count-on, not a guess.

Starting from the smaller group also works. Starting from a number you did not count does not.

Figure. Hold 8 and count five more words: 9, 10, 11, 12, 13. That last word is the join.

How it works

  1. Hold the larger countKeep 8.
  2. Count the other group onFive next words.
  3. Stop at the last on-wordThat is the join.

6The plus and minus marks come last

The story names the action first: join, or leave. The mark is the last thing you write.

A page of marks with no story is not yet this chapter’s work.

Figure. Name the action first: join or leave. Count each group. Write plus or minus last.

How it works

  1. Say the actionJoin, or take away.
  2. Count each groupDo not invent a group.
  3. Write the mark lastPlus for join, minus for leave.

7Check a take-away by joining back

If 9 take 4 is 5, then 5 join 4 must be 9. A check that fails means the take-away was wrong.

The opposite action is the test. A new story is not the test.

Figure. If 9 take 4 is 5, then 5 join 4 must be 9. The opposite action is the test.

How it works

  1. Write the take-away9 − 4 = 5.
  2. Join the part back5 + 4.
  3. Demand the startMust be 9.

8A missing addend is a subtraction

“8 and how many make 13?” is asking for the missing join. That missing number is 13 take 8.

It is still one story: a part is unknown. Do not invent a third group.

Figure. 8 and how many make 13? The missing join is 13 take 8, which is 5.

How it works

  1. Name the total13.
  2. Name the known part8.
  3. Take the known part out13 − 8 = 5.
8 and how many make 13?
  1. 5
  2. 21
  3. 8

The missing addend is 13 - 8 = 5.

Notes

  • The official chapter title is “How Many? (Addition and Subtraction of Single Digit Numbers)”. Teach the school test for that title, not a contest shortcut.
  • If a step needs a later class, stop. The next official chapter will pick it up.

Formulas

  • Join: start + new = now.
  • Take-away: start - left = remain.
  • Check: remain + left = start.

Recap

Hold these pegs from the official chapter “How Many? (Addition and Subtraction of Single Digit Numbers)”. The wording is ExamMaster’s teaching, not a textbook recap.

People joining a park is an addition story
People who join the park add to the group you already counted.
People leaving is a take-away story
People who leave are a counted part taken out.
Join two single-digit groups
8 and 5 join to 13 only after both groups have been counted.
Take away a single-digit part
9 take away 4 is 5 when four counted people actually leave.
Count on from the larger group
To join 8 and 5, hold 8 and count five more words: 9, 10, 11, 12, 13.
The plus and minus marks come last
The story names the action first: join, or leave.

Practise How Many? (Addition and Subtraction of Single Digit Numbers)

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