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Error Checking Practice Questions with Answers

Practice with 30 sample questions organized by difficulty. Click “Show Answer” to reveal the correct answer and explanation.

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Easy

Easy #1
Original
1. 123990
2. 996227
3. 341366
4. 899385
5. 822147
Copy
1. 123990
2. 969227
3. 341366
4. 839385
5. 822147
A. 2
B. 3
C. 1
D. 0

Answer: A

Explanation:

Errors found in rows: 2, 4

Row 2: "996227" vs "969227" (transposition)
Row 4: "899385" vs "839385" (format shift)
Easy #2
Original
1. 146506
2. 483917
3. 279068
4. 235262
5. 510699
Copy
1. 146506
2. 383917
3. 279068
4. 235362
5. 510699
A. 2
B. 0
C. 3
D. 1

Answer: A

Explanation:

Errors found in rows: 2, 4

Row 2: "483917" vs "383917" (keyboard proximity)
Row 4: "235262" vs "235362" (keyboard proximity)
Easy #3
Original
1. 272213
2. 609463
3. 178437
4. 940499
5. 520414
Copy
1. 272213
2. 609463
3. 178437
4. 940994
5. 5 20414
A. 3
B. 2
C. 0
D. 1

Answer: B

Explanation:

Errors found in rows: 4, 5

Row 4: "940499" vs "940994" (reversal)
Row 5: "520414" vs "5 20414" (spacing error)
Easy #4
Original
1. 365636
2. 476825
3. 537773
4. 997049
5. 845225
Copy
1. 365636
2. 476825
3. 537373
4. 997049
5. 865225
A. 3
B. 0
C. 2
D. 1

Answer: C

Explanation:

Errors found in rows: 3, 5

Row 3: "537773" vs "537373" (format shift)
Row 5: "845225" vs "865225" (phonetic)
Easy #5
Original
1. 232630
2. 457769
3. 773776
4. 551666
5. 254367
Copy
1. 232630
2. 457769
3. 7 73776
4. 551666
5. 254167
A. 0
B. 2
C. 1
D. 3

Answer: B

Explanation:

Errors found in rows: 3, 5

Row 3: "773776" vs "7 73776" (spacing error)
Row 5: "254367" vs "254167" (substitution)
Easy #6
Original
1. 941053
2. 964964
3. 516792
4. 446568
5. 553777
Copy
1. 941053
2. 96496
3. 516792
4. 44656B
5. 553777
A. 0
B. 2
C. 1
D. 3

Answer: B

Explanation:

Errors found in rows: 2, 4

Row 2: "964964" vs "96496" (omission)
Row 4: "446568" vs "44656B" (visual confusion)
Easy #7
Original
1. 260893
2. 660816
3. 654032
4. 852256
5. 286278
Copy
1. 620893
2. 660816
3. 654032
4. 852266
5. 286278
A. 2
B. 1
C. 3
D. 0

Answer: A

Explanation:

Errors found in rows: 1, 4

Row 1: "260893" vs "620893" (transposition)
Row 4: "852256" vs "852266" (phonetic)
Easy #8
Original
1. 206771
2. 446320
3. 375322
4. 955457
5. 153799
Copy
1. 206771
2. 446320
3. 375322
4. 955754
5. 193799
A. 0
B. 2
C. 1
D. 3

Answer: B

Explanation:

Errors found in rows: 4, 5

Row 4: "955457" vs "955754" (reversal)
Row 5: "153799" vs "193799" (format shift)
Easy #9
Original
1. 476675
2. 640143
3. 657238
4. 800060
5. 552838
Copy
1. 476675
2. 64014 3
3. 657238
4. 8000060
5. 552838
A. 3
B. 2
C. 0
D. 1

Answer: B

Explanation:

Errors found in rows: 2, 4

Row 2: "640143" vs "64014 3" (spacing error)
Row 4: "800060" vs "8000060" (repeated character)
Easy #10
Original
1. 515522
2. 796869
3. 422461
4. 291987
5. 114606
Copy
1. 515522
2. 796869
3. 422461
4. 291937
5. 111606
A. 3
B. 0
C. 1
D. 2

Answer: D

Explanation:

Errors found in rows: 4, 5

Row 4: "291987" vs "291937" (substitution)
Row 5: "114606" vs "111606" (case flip)

Medium

Medium #11
Original
1. YA-2974
2. FG-7441
3. WW-3244
4. XS-9935
5. PP-1330
6. FH-8847
Copy
1. YA-2974
2. FG-7441
3. WW-3244
4. XS-935
5. P-P1303
6. FH-B847
A. 3
B. 1
C. 2
D. 4
E. 0

Answer: A

Explanation:

Errors found in rows: 4, 5, 6

Row 4: "XS-9935" vs "XS-935" (omission)
Row 5: "PP-1330" vs "P-P1303" (transposition)
Row 6: "FH-8847" vs "FH-B847" (visual confusion)
Medium #12
Original
1. 406186
2. 214087
3. 989122
4. 652784
5. 523677
6. 400402
Copy
1. 40618G
2. 214007
3. 989122
4. 652784
5. 513677
6. 400402
A. 1
B. 2
C. 0
D. 4
E. 3

Answer: E

Explanation:

Errors found in rows: 1, 2, 5

Row 1: "406186" vs "40618G" (visual confusion)
Row 2: "214087" vs "214007" (phonetic)
Row 5: "523677" vs "513677" (keyboard proximity)
Medium #13
Original
1. HZ-2957
2. KJ-7468
3. FR-8318
4. SZ-4039
5. HF-9581
6. ZA-2650
Copy
1. HZ-2957
2. KN-7468
3. FR-8118
4. SZ-4039
5. HF-9581
6. ZA-Z650
A. 2
B. 4
C. 3
D. 0
E. 1

Answer: C

Explanation:

Errors found in rows: 2, 3, 6

Row 2: "KJ-7468" vs "KN-7468" (keyboard proximity)
Row 3: "FR-8318" vs "FR-8118" (substitution)
Row 6: "ZA-2650" vs "ZA-Z650" (visual confusion)
Medium #14
Original
1. 2023-03-10
2. 05:46
3. 2023-11-29
4. 16:57
5. 00:53
6. 2020-07-18
Copy
1. 2033-03-10
2. 05:46
3. 2023-11-29
4. 16:57
5. 00.53
6. 2020-13-18
A. 0
B. 1
C. 2
D. 4
E. 3

Answer: E

Explanation:

Errors found in rows: 1, 5, 6

Row 1: "2023-03-10" vs "2033-03-10" (substitution)
Row 5: "00:53" vs "00.53" (format shift)
Row 6: "2020-07-18" vs "2020-13-18" (invalid date)
Medium #15
Original
1. VP-3381
2. SM-7156
3. NN-3244
4. TX-0724
5. KA-1379
6. PW-0883
Copy
1. VP-3381
2. SM-71556
3. NN-8244
4. TX-0724
5. KA-1379
6. PW- 0883
A. 3
B. 2
C. 4
D. 0
E. 1

Answer: A

Explanation:

Errors found in rows: 2, 3, 6

Row 2: "SM-7156" vs "SM-71556" (repeated character)
Row 3: "NN-3244" vs "NN-8244" (substitution)
Row 6: "PW-0883" vs "PW- 0883" (spacing error)
Medium #16
Original
1. 695056
2. 663586
3. 290772
4. 201782
5. 139657
6. 529562
Copy
1. 795056
2. 663856
3. 290772
4. 201782
5. 139657
6. 5296562
A. 0
B. 1
C. 2
D. 4
E. 3

Answer: E

Explanation:

Errors found in rows: 1, 2, 6

Row 1: "695056" vs "795056" (format shift)
Row 2: "663586" vs "663856" (transposition)
Row 6: "529562" vs "5296562" (addition)
Medium #17
Original
1. 234471
2. 847855
3. 295825
4. 600370
5. 407413
6. 700033
Copy
1. 234471
2. 847855
3. 295828
4. 6O0370
5. 407413
6. 700533
A. 3
B. 2
C. 1
D. 4
E. 0

Answer: A

Explanation:

Errors found in rows: 3, 4, 6

Row 3: "295825" vs "295828" (case flip)
Row 4: "600370" vs "6O0370" (visual confusion)
Row 6: "700033" vs "700533" (format shift)
Medium #18
Original
1. UG-5905
2. YV-8799
3. LC-8009
4. FW-0605
5. DV-4907
6. KK-6053
Copy
1. UG-5905
2. YV-8799
3. LC-9008
4. FG-0605
5. DF-4907
6. KK-6053
A. 4
B. 2
C. 0
D. 3
E. 1

Answer: D

Explanation:

Errors found in rows: 3, 4, 5

Row 3: "LC-8009" vs "LC-9008" (reversal)
Row 4: "FW-0605" vs "FG-0605" (substitution)
Row 5: "DV-4907" vs "DF-4907" (phonetic)
Medium #19
Original
1. 605896
2. 720649
3. 789250
4. 827690
5. 286907
6. 491949
Copy
1. 6058946
2. 720649
3. 789250
4. 827690
5. 28690 7
6. 499491
A. 2
B. 4
C. 0
D. 1
E. 3

Answer: E

Explanation:

Errors found in rows: 1, 5, 6

Row 1: "605896" vs "6058946" (addition)
Row 5: "286907" vs "28690 7" (spacing error)
Row 6: "491949" vs "499491" (reversal)
Medium #20
Original
1. 2021-03-07
2. 05/11/2022
3. 2023-01-06
4. 22/05/2020
5. 2022-11-26
6. 04:08
Copy
1. 2021-03-07
2. 05/11/2022
3. 2023-10-06
4. 32/05/2020
5. 2022/11/26
6. 04:08
A. 2
B. 4
C. 3
D. 0
E. 1

Answer: C

Explanation:

Errors found in rows: 3, 4, 5

Row 3: "2023-01-06" vs "2023-10-06" (transposition)
Row 4: "22/05/2020" vs "32/05/2020" (invalid date)
Row 5: "2022-11-26" vs "2022/11/26" (format shift)

Hard

Hard #21
Original
1. 2023-04-27
2. 29/01/2020
3. 2022-10-20
4. 20/05/2023
5. 02:14
6. 2025-07-01
7. 2021-09-23
8. 2020-10-16
Copy
1. 2023-04-27
2. 29/01/2020
3. 2822-10-20
4. 20/85/2023
5. 02:14
6. 2025-07-10
7. 2021-09-23
8. 2020/10/16
A. 2
B. 3
C. 4
D. 1
E. 5
F. 0

Answer: C

Explanation:

Errors found in rows: 3, 4, 6, 8

Row 3: "2022-10-20" vs "2822-10-20" (substitution)
Row 4: "20/05/2023" vs "20/85/2023" (substitution)
Row 6: "2025-07-01" vs "2025-07-10" (transposition)
Row 8: "2020-10-16" vs "2020/10/16" (format shift)
Hard #22
Original
1. AP-2116
2. ML-9895
3. QC-3360
4. EU-4995
5. PG-8136
6. QW-4873
7. GA-7065
8. ED-1343
Copy
1. Ap-2116
2. ML-9895
3. QRC-3360
4. EU-4995
5. PG-8436
6. QW-873
7. GA-7065
8. ED-1343
A. 2
B. 1
C. 0
D. 3
E. 5
F. 4

Answer: F

Explanation:

Errors found in rows: 1, 3, 5, 6

Row 1: "AP-2116" vs "Ap-2116" (case flip)
Row 3: "QC-3360" vs "QRC-3360" (addition)
Row 5: "PG-8136" vs "PG-8436" (substitution)
Row 6: "QW-4873" vs "QW-873" (omission)
Hard #23
Original
1. N6YS1A
2. GEMDDF
3. LV-1279
4. HQAD95
5. JQ-8916
6. 464624
7. FFG6R3
8. 424424
Copy
1. N6YS1B
2. GEMDDF
3. LV-1279
4. DAQH95
5. JQ-8916
6. 464624
7. FFGGR3
8. 422444
A. 5
B. 3
C. 0
D. 2
E. 1
F. 4

Answer: F

Explanation:

Errors found in rows: 1, 4, 7, 8

Row 1: "N6YS1A" vs "N6YS1B" (format shift)
Row 4: "HQAD95" vs "DAQH95" (reversal)
Row 7: "FFG6R3" vs "FFGGR3" (visual confusion)
Row 8: "424424" vs "422444" (reversal)
Hard #24
Original
1. 551869
2. 736626
3. 415388
4. 976033
5. 512706
6. 638681
7. 487464
8. 788279
Copy
1. 553869
2. 736626
3. 414388
4. 976033
5. 512706
6. 683681
7. 487464
8. 782279
A. 1
B. 2
C. 0
D. 3
E. 4
F. 5

Answer: E

Explanation:

Errors found in rows: 1, 3, 6, 8

Row 1: "551869" vs "553869" (phonetic)
Row 3: "415388" vs "414388" (keyboard proximity)
Row 6: "638681" vs "683681" (reversal)
Row 8: "788279" vs "782279" (substitution)
Hard #25
Original
1. 2020-02-06
2. 24/05/2023
3. 23/04/2024
4. 18:33
5. 05:24
6. 04/07/2021
7. 2021-12-01
8. 16/12/2024
Copy
1. 2020-02-06
2. 24/05/2023
3. 23-04-2024
4. 18.33
5. 05:24
6. 04/07/2021
7. 2021/12/01
8. 16/12/2029
A. 3
B. 2
C. 0
D. 5
E. 1
F. 4

Answer: F

Explanation:

Errors found in rows: 3, 4, 7, 8

Row 3: "23/04/2024" vs "23-04-2024" (format shift)
Row 4: "18:33" vs "18.33" (format shift)
Row 7: "2021-12-01" vs "2021/12/01" (format shift)
Row 8: "16/12/2024" vs "16/12/2029" (substitution)
Hard #26
Original
1. 20/09/2024
2. 03:02
3. 08/12/2024
4. 07:10
5. 2024-09-15
6. 2023-10-13
7. 2024-08-19
8. 2025-04-26
Copy
1. 20/09/2024
2. 08:02
3. 08/12/2024
4. 25:10
5. 2204-09-15
6. 2023-13-13
7. 2024-08-19
8. 2025-04-26
A. 1
B. 3
C. 2
D. 5
E. 4
F. 0

Answer: E

Explanation:

Errors found in rows: 2, 4, 5, 6

Row 2: "03:02" vs "08:02" (substitution)
Row 4: "07:10" vs "25:10" (invalid date)
Row 5: "2024-09-15" vs "2204-09-15" (transposition)
Row 6: "2023-10-13" vs "2023-13-13" (invalid date)
Hard #27
Format rule: letter-digit-letter space digit-letter-digit
A1B 2C3
Code
1. J3W 5A9
2. 4AZ 7H1
3. X0G 6V2
4. T8L 7Q2
5. F3S 3F9
6. F3U 9G7
7. Q3T 4E8
8. 2KX 4K0
How many codes violate the format rule?
A. 3
B. 4
C. 0
D. 1
E. 2
F. 5

Answer: E

Explanation:

Violations found in rows: 2, 8

Row 2: "4AZ 7H1" does not match the format
Row 8: "2KX 4K0" does not match the format
Hard #28
Format rule: 3 uppercase letters, hyphen, 4 digits
ABC-1234
Code
1. GRV-6911
2. BQJ-1060
3. KHE-6641
4. dYW-2966
5. TLF-2561
6. eVG-2588
7. MDE-9039
8. GRE-314
How many codes violate the format rule?
A. 1
B. 0
C. 5
D. 3
E. 2
F. 4

Answer: D

Explanation:

Violations found in rows: 4, 6, 8

Row 4: "dYW-2966" does not match the format
Row 6: "eVG-2588" does not match the format
Row 8: "GRE-314" does not match the format
Hard #29
Original
1. 652851
2. 298196
3. 669459
4. 388260
5. 859044
6. 354010
7. 240854
8. 349312
Copy
1. 652851
2. 298166
3. 669459
4. 38260
5. 095844
6. 354001
7. 240854
8. 349312
A. 2
B. 5
C. 0
D. 1
E. 4
F. 3

Answer: E

Explanation:

Errors found in rows: 2, 4, 5, 6

Row 2: "298196" vs "298166" (substitution)
Row 4: "388260" vs "38260" (omission)
Row 5: "859044" vs "095844" (reversal)
Row 6: "354010" vs "354001" (transposition)
Hard #30
Original
1. YW6UHK
2. 522350
3. SY-8300
4. 820711
5. ZL-9327
6. PX5HR2
7. 299940
8. 1V5QHR
Copy
1. YW6UGK
2. 522350
3. SY-800
4. 8220711
5. 2L-9327
6. PX5HR2
7. 299940
8. 1V5QHR
A. 3
B. 4
C. 1
D. 2
E. 0
F. 5

Answer: B

Explanation:

Errors found in rows: 1, 3, 4, 5

Row 1: "YW6UHK" vs "YW6UGK" (keyboard proximity)
Row 3: "SY-8300" vs "SY-800" (omission)
Row 4: "820711" vs "8220711" (repeated character)
Row 5: "ZL-9327" vs "2L-9327" (visual confusion)

Frequently Asked Questions

Look for transpositions (1234 vs 1324), substitutions (1234 vs 1284), missing characters (1234 vs 134), and extra characters (1234 vs 12345). Errors are subtle, so check each character carefully.
Banks, accounting firms, insurance companies, law firms, healthcare organizations, and any role involving data entry or document processing. SHL, Talent Q, and Cubiks all offer error checking assessments.
Scan systematically row by row, character by character. Use a finger or cursor to track position. Focus on one row at a time. Practice improves speed and accuracy—aim for zero errors before speeding up.
Each comparison is procedurally generated using realistic data formats including numbers, alphanumeric codes, and text strings. The system introduces specific error types — transpositions, substitutions, insertions, and deletions — at controlled rates based on the difficulty level. This ensures every practice set is unique and has a single correct answer.