Grade 2 Mathematics Numbers Concept – Filling In Missing Numbers Notes
Mathematics — Numbers Concept
Subtopic: Filling In Missing Numbers (Age 7 — Kenya)
Learning goals:
- Find the number before, after and between small numbers (0–100).
- Fill in missing numbers in counting patterns (+1, −1, +2, +5, +10).
- Use number lines and real objects (mangoes, pencils) to help find missing numbers.
Key ideas
- If we count up by 1, each number is 1 more than the one before it. Example: 6, 7, 8.
- To find the number before, subtract 1. To find the number after, add 1.
- Some patterns skip numbers: count by 2s (2, 4, 6…), by 5s (5, 10, 15…), and by 10s (10, 20, 30…).
Visual idea — number boxes
We can show a missing number as an empty box. Fill the box with the correct number.
Example: 3, ?, 5. What is the missing number? Count: 3, 4, 5. So the missing number is 4.
Example 1 — Number before and after
Find the number before 9 and the number after 9.
Example 2 — Counting forward by 2s
Fill the missing number: 2, 4, ?, 8.
We are adding 2 each time: 2 → 4 → 6 → 8. So the missing number is 6.
Number line — use it to help
A number line shows numbers in order. Put a mark where the missing number is.
If we want the number between 4 and 6, look on the line: it is 5.
Use real objects
Use pencils, stones, or mangoes to count. If you have 5 mangoes and you eat 1, how many left? 5 − 1 = 4.
Practice — fill the missing number
Easy
- 7, __, 9
- __ , 11, 12
- 4, 5, __
- __ , 1, 2
Medium
- 10, __, 12
- 3, __, 7 (count by 2s)
- __ , 15, 20 (count by 5s)
- 29, __, 31
Challenge (Try with a number line or objects)
- __ , 41, 42
- 20, __, 40 (count by 10s)
Answers
- Easy: 1) 8 2) 10 3) 6 4) 0
- Medium: 1) 11 2) 5 3) 10 or 5→10→15→20 (so missing is 10) 4) 30
- Challenge: 1) 40 2) 30
Teacher/Parent tip: Let the child use real things from home or school (buttons, stones, maize kernels) to build the sequence. Ask them to say the numbers aloud while placing each object — this helps memory and understanding.