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Missing sequence terms
Use the constant step size between terms to find the missing middle number in a sequence. Review suitability for your learners before teaching.
Worksheet StudioPractice pack · Ages 7-9
Missing sequence terms
Take your time. Show your thinking.
1. Find the missing number in the sequence: 15, 21, ____, 33, 39.
2. Find the missing number in the sequence: 5, 13, ____, 29, 37.
3. Find the missing number in the sequence: 15, 19, ____, 27, 31.
4. Find the missing number in the sequence: 17, 26, ____, 44, 53.
5. Find the missing number in the sequence: 16, 19, ____, 25, 28.
6. Find the missing number in the sequence: 19, 26, ____, 40, 47.
7. Find the missing number in the sequence: 11, 20, ____, 38, 47.
8. Find the missing number in the sequence: 5, 9, ____, 17, 21.
9. Find the missing number in the sequence: 1, 10, ____, 28, 37.
10. Find the missing number in the sequence: 3, 12, ____, 30, 39.
11. Find the missing number in the sequence: 12, 20, ____, 36, 44.
12. Find the missing number in the sequence: 6, 16, ____, 36, 46.
12 questions · Seed 68 · Age guidance, not curriculum certification
View the answer key
Worksheet StudioAnswer key · Ages 7-9
Missing sequence terms
Answers and reasoning. Review before teaching.
1. Find the missing number in the sequence: 15, 21, ____, 33, 39.
27The sequence increases by 6 each step: 21 + 6 = 27.
2. Find the missing number in the sequence: 5, 13, ____, 29, 37.
21The sequence increases by 8 each step: 13 + 8 = 21.
3. Find the missing number in the sequence: 15, 19, ____, 27, 31.
23The sequence increases by 4 each step: 19 + 4 = 23.
4. Find the missing number in the sequence: 17, 26, ____, 44, 53.
35The sequence increases by 9 each step: 26 + 9 = 35.
5. Find the missing number in the sequence: 16, 19, ____, 25, 28.
22The sequence increases by 3 each step: 19 + 3 = 22.
6. Find the missing number in the sequence: 19, 26, ____, 40, 47.
33The sequence increases by 7 each step: 26 + 7 = 33.
7. Find the missing number in the sequence: 11, 20, ____, 38, 47.
29The sequence increases by 9 each step: 20 + 9 = 29.
8. Find the missing number in the sequence: 5, 9, ____, 17, 21.
13The sequence increases by 4 each step: 9 + 4 = 13.
9. Find the missing number in the sequence: 1, 10, ____, 28, 37.
19The sequence increases by 9 each step: 10 + 9 = 19.
10. Find the missing number in the sequence: 3, 12, ____, 30, 39.
21The sequence increases by 9 each step: 12 + 9 = 21.
11. Find the missing number in the sequence: 12, 20, ____, 36, 44.
28The sequence increases by 8 each step: 20 + 8 = 28.
12. Find the missing number in the sequence: 6, 16, ____, 36, 46.
26The sequence increases by 10 each step: 16 + 10 = 26.
12 questions · Seed 68 · Age guidance, not curriculum certification
Worksheet StudioPractice pack · Ages 7-9
Missing sequence terms
Take your time. Show your thinking.
1. Find the missing number in the sequence: 15, 21, ____, 33, 39.
2. Find the missing number in the sequence: 5, 13, ____, 29, 37.
3. Find the missing number in the sequence: 15, 19, ____, 27, 31.
4. Find the missing number in the sequence: 17, 26, ____, 44, 53.
5. Find the missing number in the sequence: 16, 19, ____, 25, 28.
6. Find the missing number in the sequence: 19, 26, ____, 40, 47.
7. Find the missing number in the sequence: 11, 20, ____, 38, 47.
8. Find the missing number in the sequence: 5, 9, ____, 17, 21.
9. Find the missing number in the sequence: 1, 10, ____, 28, 37.
10. Find the missing number in the sequence: 3, 12, ____, 30, 39.
11. Find the missing number in the sequence: 12, 20, ____, 36, 44.
12. Find the missing number in the sequence: 6, 16, ____, 36, 46.
12 questions · Seed 68 · Age guidance, not curriculum certification
Worksheet StudioAnswer key · Ages 7-9
Missing sequence terms
Answers and reasoning. Review before teaching.
1. Find the missing number in the sequence: 15, 21, ____, 33, 39.
27The sequence increases by 6 each step: 21 + 6 = 27.
2. Find the missing number in the sequence: 5, 13, ____, 29, 37.
21The sequence increases by 8 each step: 13 + 8 = 21.
3. Find the missing number in the sequence: 15, 19, ____, 27, 31.
23The sequence increases by 4 each step: 19 + 4 = 23.
4. Find the missing number in the sequence: 17, 26, ____, 44, 53.
35The sequence increases by 9 each step: 26 + 9 = 35.
5. Find the missing number in the sequence: 16, 19, ____, 25, 28.
22The sequence increases by 3 each step: 19 + 3 = 22.
6. Find the missing number in the sequence: 19, 26, ____, 40, 47.
33The sequence increases by 7 each step: 26 + 7 = 33.
7. Find the missing number in the sequence: 11, 20, ____, 38, 47.
29The sequence increases by 9 each step: 20 + 9 = 29.
8. Find the missing number in the sequence: 5, 9, ____, 17, 21.
13The sequence increases by 4 each step: 9 + 4 = 13.
9. Find the missing number in the sequence: 1, 10, ____, 28, 37.
19The sequence increases by 9 each step: 10 + 9 = 19.
10. Find the missing number in the sequence: 3, 12, ____, 30, 39.
21The sequence increases by 9 each step: 12 + 9 = 21.
11. Find the missing number in the sequence: 12, 20, ____, 36, 44.
28The sequence increases by 8 each step: 20 + 8 = 28.
12. Find the missing number in the sequence: 6, 16, ____, 36, 46.
26The sequence increases by 10 each step: 16 + 10 = 26.
12 questions · Seed 68 · Age guidance, not curriculum certification