UST Elementary Daily Math Challenge
Week 9 — Counting & Combinations
October 12–18, 2026
50 Problems • Grades 3–5 Focus
A little math every day. A little stronger every week.
Weekly Format
每天完成一小部分；周末完成 Challenge
2
Monday: Questions 1–10
Tuesday: Questions 11–20
Wednesday: Questions 21–30
Thursday: Questions 31–40
Friday / Weekend: Questions 41–50 + Challenge
Goal: Think first, calculate second, and explain your reasoning.
Daily Practice
Questions 1–5
3
1. You have 3 shirts and 2 pairs of pants. How many outfits? A) 5 B) 6 C) 3 D) 2
2. You have 4 shirts and 2 pairs of pants. How many outfits? A) 6 B) 8 C) 4 D) 2
3. You have 2 shirts and 2 pairs of pants. How many outfits? A) 4 B) 4 C) 2 D) 2
4. You have 3 shirts and 2 pairs of pants. How many outfits? A) 5 B) 6 C) 3 D) 2
5. You have 4 shirts and 2 pairs of pants. How many outfits? A) 6 B) 8 C) 4 D) 2
Daily Practice
Questions 6–10
4
6. You have 2 shirts and 2 pairs of pants. How many outfits? A) 4 B) 4 C) 2 D) 2
7. You have 3 shirts and 2 pairs of pants. How many outfits? A) 5 B) 6 C) 3 D) 2
8. You have 4 shirts and 2 pairs of pants. How many outfits? A) 6 B) 8 C) 4 D) 2
9. You have 2 shirts and 2 pairs of pants. How many outfits? A) 4 B) 4 C) 2 D) 2
10. You have 3 shirts and 2 pairs of pants. How many outfits? A) 5 B) 6 C) 3 D) 2
Daily Practice
Questions 11–15
5
11. You have 4 shirts and 2 pairs of pants. How many outfits? A) 6 B) 8 C) 4 D) 2
12. You have 2 shirts and 2 pairs of pants. How many outfits? A) 4 B) 4 C) 2 D) 2
13. You have 3 shirts and 2 pairs of pants. How many outfits? A) 5 B) 6 C) 3 D) 2
14. You have 4 shirts and 2 pairs of pants. How many outfits? A) 6 B) 8 C) 4 D) 2
15. You have 2 shirts and 2 pairs of pants. How many outfits? A) 4 B) 4 C) 2 D) 2
Daily Practice
Questions 16–20
6
16. There are 2 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
17. There are 3 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
18. There are 4 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
19. There are 5 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
20. There are 2 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
Daily Practice
Questions 21–25
7
21. There are 3 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
22. There are 4 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
23. There are 5 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
24. There are 2 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
25. There are 3 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
Daily Practice
Questions 26–30
8
26. There are 4 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
27. There are 5 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
28. There are 2 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
29. There are 3 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
30. There are 4 drink choices and 3 snack choices. Number of different drink-snack pairs = ___.
Daily Practice
Questions 31–35
9
31. A path has 2 choices at the first turn and 3 choices at the second. How many possible routes?
32. A path has 2 choices at the first turn and 4 choices at the second. How many possible routes?
33. A path has 2 choices at the first turn and 2 choices at the second. How many possible routes?
34. A path has 2 choices at the first turn and 3 choices at the second. How many possible routes?
35. A path has 2 choices at the first turn and 4 choices at the second. How many possible routes?
Daily Practice
Questions 36–40
10
36. A path has 2 choices at the first turn and 2 choices at the second. How many possible routes?
37. A path has 2 choices at the first turn and 3 choices at the second. How many possible routes?
38. A path has 2 choices at the first turn and 4 choices at the second. How many possible routes?
39. A path has 2 choices at the first turn and 2 choices at the second. How many possible routes?
40. A path has 2 choices at the first turn and 3 choices at the second. How many possible routes?
Daily Practice
Questions 41–45
11
41. A path has 2 choices at the first turn and 4 choices at the second. How many possible routes?
42. A path has 2 choices at the first turn and 2 choices at the second. How many possible routes?
43. A path has 2 choices at the first turn and 3 choices at the second. How many possible routes?
44. A path has 2 choices at the first turn and 4 choices at the second. How many possible routes?
45. A path has 2 choices at the first turn and 2 choices at the second. How many possible routes?
Weekly Challenge
Questions 46–50
12
46. Challenge: How many 2-letter codes can be made using A, B, C if repetition is allowed?
47. Challenge: How many 2-letter codes can be made using A, B, C if repetition is allowed?
48. Challenge: How many 2-letter codes can be made using A, B, C if repetition is allowed?
49. Challenge: How many 2-letter codes can be made using A, B, C if repetition is allowed?
50. Challenge: How many 2-letter codes can be made using A, B, C if repetition is allowed?
Answer Key — Questions 1–5
Answer + How to Solve
13
1. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
2. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
3. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
4. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
5. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
Answer Key — Questions 6–10
Answer + How to Solve
14
6. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
7. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
8. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
9. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
10. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
Answer Key — Questions 11–15
Answer + How to Solve
15
11. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
12. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
13. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
14. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
15. Answer: B
How to solve: Each shirt can pair with each pair of pants: multiply the choices.
Answer Key — Questions 16–20
Answer + How to Solve
16
16. Answer: 6
How to solve: Use the multiplication principle: choices × choices.
17. Answer: 9
How to solve: Use the multiplication principle: choices × choices.
18. Answer: 12
How to solve: Use the multiplication principle: choices × choices.
19. Answer: 15
How to solve: Use the multiplication principle: choices × choices.
20. Answer: 6
How to solve: Use the multiplication principle: choices × choices.
Answer Key — Questions 21–25
Answer + How to Solve
17
21. Answer: 9
How to solve: Use the multiplication principle: choices × choices.
22. Answer: 12
How to solve: Use the multiplication principle: choices × choices.
23. Answer: 15
How to solve: Use the multiplication principle: choices × choices.
24. Answer: 6
How to solve: Use the multiplication principle: choices × choices.
25. Answer: 9
How to solve: Use the multiplication principle: choices × choices.
Answer Key — Questions 26–30
Answer + How to Solve
18
26. Answer: 12
How to solve: Use the multiplication principle: choices × choices.
27. Answer: 15
How to solve: Use the multiplication principle: choices × choices.
28. Answer: 6
How to solve: Use the multiplication principle: choices × choices.
29. Answer: 9
How to solve: Use the multiplication principle: choices × choices.
30. Answer: 12
How to solve: Use the multiplication principle: choices × choices.
Answer Key — Questions 31–35
Answer + How to Solve
19
31. Answer: 6
How to solve: Multiply the number of choices at each stage.
32. Answer: 8
How to solve: Multiply the number of choices at each stage.
33. Answer: 4
How to solve: Multiply the number of choices at each stage.
34. Answer: 6
How to solve: Multiply the number of choices at each stage.
35. Answer: 8
How to solve: Multiply the number of choices at each stage.
Answer Key — Questions 36–40
Answer + How to Solve
20
36. Answer: 4
How to solve: Multiply the number of choices at each stage.
37. Answer: 6
How to solve: Multiply the number of choices at each stage.
38. Answer: 8
How to solve: Multiply the number of choices at each stage.
39. Answer: 4
How to solve: Multiply the number of choices at each stage.
40. Answer: 6
How to solve: Multiply the number of choices at each stage.
Answer Key — Questions 41–45
Answer + How to Solve
21
41. Answer: 8
How to solve: Multiply the number of choices at each stage.
42. Answer: 4
How to solve: Multiply the number of choices at each stage.
43. Answer: 6
How to solve: Multiply the number of choices at each stage.
44. Answer: 8
How to solve: Multiply the number of choices at each stage.
45. Answer: 4
How to solve: Multiply the number of choices at each stage.
Answer Key — Questions 46–50
Answer + How to Solve
22
46. Answer: 9
How to solve: There are 3 choices for the first letter and 3 for the second: 3×3=9.
47. Answer: 9
How to solve: There are 3 choices for the first letter and 3 for the second: 3×3=9.
48. Answer: 9
How to solve: There are 3 choices for the first letter and 3 for the second: 3×3=9.
49. Answer: 9
How to solve: There are 3 choices for the first letter and 3 for the second: 3×3=9.
50. Answer: 9
How to solve: There are 3 choices for the first letter and 3 for the second: 3×3=9.
Week Complete!
Think • Reason • Solve • Explain