6 7 4 8 5 9 8 4 8 3 2 5 8 6 7 8 3 8. Using the above sequence find the number that does not belong to the group 688, 426, 542, 287.
287
Number the 18 digits by position: 1:6, 2:7, 3:4, 4:8, 5:5, 6:9, 7:8, 8:4, 9:8, 10:3, 11:2, 12:5, 13:8, 14:6, 15:7, 16:8, 17:3, 18:8. Look for a single reading rule that produces the three-digit numbers.
Step 1 — Reading every third digit (skipping two digits each time): positions 1, 4, 7 give 6, 8, 8 = 688; positions 5, 8, 11 give 5, 4, 2 = 542; positions 8, 11, 14 give 4, 2, 6 = 426.
Step 2 — For 287, the only 2 is at position 11, and the digit three places later (position 14) is 6, not 8. Its digits can only be picked at positions 11, 13, 15, which uses a different gap, so 287 cannot be formed by the same rule.
Step 3 — 688, 542 and 426 all follow the every-third-digit rule, so they belong together.
287 option is correct.
Important Questions from Arrangement and Pattern
How many such pairs of digits are there in the number ‘95126139', which have as many digits between them in the number (both forward and backward direction) as they have between them in the Numeric Series?
If all the vowels are dropped from the given arrangement, which of the following is 9th from the right end?
How many such consonants are there which are immediately followed by a consonant and immediately preceded by a vowel?
Which letter is 5th to the right of the 3rd from the left end in the given arrangement?
If in each number, all the three digits are arranged in ascending order within the number, which of the following will be the second lowest number after rearrangement?
