Let's solve the problem step by step.
The task is to
find the missing number in each equation so that the sum equals 100. These are simple addition problems where one addend is missing.
We'll go through each problem:
---
1. 15 + ___ = 100
To find the missing number:
100 - 15 =
85
✔ Answer:
85
---
2. 35 + ___ = 100
100 - 35 =
65
✔ Answer:
65
---
3. ___ + 65 = 100
100 - 65 =
35
✔ Answer:
35
---
4. ___ + 85 = 100
100 - 85 =
15
✔ Answer:
15
---
5. 75 + ___ = 100
100 - 75 =
25
✔ Answer:
25
---
6. 5 + ___ = 100
100 - 5 =
95
✔ Answer:
95
---
7. ___ + 25 = 100
100 - 25 =
75
✔ Answer:
75
---
8. ___ + 15 = 100
100 - 15 =
85
✔ Answer:
85
---
9. 45 + ___ = 100
100 - 45 =
55
✔ Answer:
55
---
10. 85 + ___ = 100
100 - 85 =
15
✔ Answer:
15
---
11. ___ + 35 = 100
100 - 35 =
65
✔ Answer:
65
---
12. ___ + 75 = 100
100 - 75 =
25
✔ Answer:
25
---
13. 25 + ___ = 100
100 - 25 =
75
✔ Answer:
75
---
14. 95 + ___ = 100
100 - 95 =
5
✔ Answer:
5
---
Final Answers:
1. 85
2. 65
3. 35
4. 15
5. 25
6. 95
7. 75
8. 85
9. 55
10. 15
11. 65
12. 25
13. 75
14. 5
---
Pattern Observation:
These are all
pairs of numbers that add up to 100, which helps build number sense and mental math skills. For example:
- 15 and 85
- 25 and 75
- 35 and 65
- 45 and 55
- etc.
You can see that the missing number is always
100 minus the given number.
This exercise helps students understand
complements to 100, a key skill in arithmetic.
✔ All solved! Let me know if you'd like this formatted as a printable answer sheet.
Parent Tip: Review the logic above to help your child master the concept of addition worksheet for 10 year olds.
