Number & Letter Series: Practice Questions with Answers
Find the next or missing term in number and letter series. Try each question first: tap an option to check it, and the explanation appears below.
Question 1Medium
What number comes next in the series: 12, 17, 25, 36, 50, ?
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✅ A. 67
Look at the differences between terms: 5, 8, 11, 14. They grow by 3 each time, so the next difference is 14 + 3 = 17. The next term is 50 + 17 = 67.
Question page →Question 2Medium
Find the missing number in the series: 5, 15, 45, ?, 405
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✅ A. 135
Each term is 3 times the one before it: 5 × 3 = 15, and so on. So the missing term is 45 × 3 = 135. Check: 135 × 3 = 405, which matches the next term.
Question page →Question 3Medium
What number comes next in the series: 3, 10, 31, 94, 283, ?
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✅ A. 850
Each term is the previous term × 3 + 1: 3 × 3 + 1 = 10, 10 × 3 + 1 = 31, 31 × 3 + 1 = 94, 94 × 3 + 1 = 283. So the next term is 283 × 3 + 1 = 850.
Question page →Question 4Medium
What number comes next in the series: 3, 8, 23, 68, 203, ?
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✅ B. 608
Each term is the previous term × 3 − 1: 3 × 3 − 1 = 8, 8 × 3 − 1 = 23, 23 × 3 − 1 = 68, 68 × 3 − 1 = 203. So the next term is 203 × 3 − 1 = 608.
Question page →Question 5Medium
What number comes next in the series: 8, 19, 41, 85, 173, ?
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✅ D. 349
Each term is the previous term × 2 + 3: 8 × 2 + 3 = 19, 19 × 2 + 3 = 41, 41 × 2 + 3 = 85, 85 × 2 + 3 = 173. So the next term is 173 × 2 + 3 = 349.
Question page →Question 6Easy
Which letter comes next in the series: B, D, F, H, J, ?
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✅ D. L
Write the alphabet positions: B = 2, D = 4, F = 6, H = 8, J = 10. Each letter is 2 places after the previous one. So the next position is 10 + 2 = 12, which is L.
Question page →Question 7Medium
Find the missing number in the series: 11, ?, 44, 88, 176
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✅ B. 22
Each term is 2 times the one before it: 11 × 2 = 22, and so on. So the missing term is 11 × 2 = 22. Check: 22 × 2 = 44, which matches the next term.
Question page →Question 8Hard
What number comes next in the series: 9, 21, 13, 16, 17, 11, 21, ?
Show answerAnswer
✅ C. 6
Two series are mixed together. The 1st, 3rd, 5th and 7th terms (9, 13, 17, 21) go up by 4. The 2nd, 4th and 6th terms (21, 16, 11) go down by 5. The missing term is the 8th, which belongs to the second series: 11 − 5 = 6.
Question page →Question 9Medium
What number comes next in the series: 2, 8, 26, 80, 242, ?
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✅ D. 728
Each term is the previous term × 3 + 2: 2 × 3 + 2 = 8, 8 × 3 + 2 = 26, 26 × 3 + 2 = 80, 80 × 3 + 2 = 242. So the next term is 242 × 3 + 2 = 728.
Question page →Question 10Easy
Which letter comes next in the series: J, M, P, S, V, ?
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✅ A. Y
Write the alphabet positions: J = 10, M = 13, P = 16, S = 19, V = 22. Each letter is 3 places after the previous one. So the next position is 22 + 3 = 25, which is Y.
Question page →Question 11Medium
Find the missing number in the series: 3, 9, ?, 81, 243
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✅ A. 27
Each term is 3 times the one before it: 3 × 3 = 9, and so on. So the missing term is 9 × 3 = 27. Check: 27 × 3 = 81, which matches the next term.
Question page →Question 12Easy
What number comes next in the series: 43, 50, 57, 64, 71, ?
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✅ A. 78
Each term is 7 more than the one before it: 50 − 43 = 7, 57 − 50 = 7, 64 − 57 = 7, 71 − 64 = 7. So the next term is 71 + 7 = 78.
Question page →Question 13Medium
What number comes next in the series: 2, 8, 15, 23, 32, ?
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✅ B. 42
Look at the differences between terms: 6, 7, 8, 9. They grow by 1 each time, so the next difference is 9 + 1 = 10. The next term is 32 + 10 = 42.
Question page →Question 14Easy
What number comes next in the series: 23, 38, 53, 68, 83, ?
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✅ B. 98
Each term is 15 more than the one before it: 38 − 23 = 15, 53 − 38 = 15, 68 − 53 = 15, 83 − 68 = 15. So the next term is 83 + 15 = 98.
Question page →Question 15Medium
What number comes next in the series: 5, 9, 17, 29, 45, ?
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✅ A. 65
Look at the differences between terms: 4, 8, 12, 16. They grow by 4 each time, so the next difference is 16 + 4 = 20. The next term is 45 + 20 = 65.
Question page →Question 16Medium
What comes next in the series: BW, DT, FQ, HN, ?
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✅ B. JK
Look at the two letters separately. The first letters B, D, F, H move 2 places forward each time, so the next is J. The second letters W, T, Q, N move 3 places back each time, so the next is K. The answer is JK.
Question page →Question 17Easy
Which letter comes next in the series: Z, U, P, K, F, ?
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✅ D. A
Write the alphabet positions: Z = 26, U = 21, P = 16, K = 11, F = 6. Each letter is 5 places before the previous one. So the next position is 6 − 5 = 1, which is A.
Question page →Question 18Easy
Which letter comes next in the series: D, H, L, P, T, ?
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✅ A. X
Write the alphabet positions: D = 4, H = 8, L = 12, P = 16, T = 20. Each letter is 4 places after the previous one. So the next position is 20 + 4 = 24, which is X.
Question page →Question 19Hard
What number comes next in the series: 5, 59, 11, 63, 17, 67, 23, ?
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✅ A. 71
Two series are mixed together. The 1st, 3rd, 5th and 7th terms (5, 11, 17, 23) go up by 6. The 2nd, 4th and 6th terms (59, 63, 67) go up by 4. The missing term is the 8th, which belongs to the second series: 67 + 4 = 71.
Question page →Question 20Easy
What number comes next in the series: 2, 9, 16, 23, 30, ?
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✅ C. 37
Each term is 7 more than the one before it: 9 − 2 = 7, 16 − 9 = 7, 23 − 16 = 7, 30 − 23 = 7. So the next term is 30 + 7 = 37.
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