# Find the number that does not fit into the pattern shown below

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

12 34 56 78 910 1112 1314 1516 1718 1920 2122 2324 2526 2728 2930 3132 3334 3536

Each row forms a set which implements a pattern. The two patterns are similar but not essentially the same. However, one row contains an element that does not fit into the pattern. Find this element.

• You have posted several intriguing puzzles which do not seem to have any direction given or much commentary on answers. Apparently no-one can solve them correctly. Do they each have a definitive answer? – Weather Vane Sep 6 '19 at 21:08

I think(partial):

2122

In the second row,
$$1920$$ can be expressed as $$910 *2+100$$.
$$2324$$ can be expressed as $$1112*2+100$$.
$$2728$$ can be expressed as $$1314*2+100$$... and so on
But $$2122$$ is the only number which cannot be expressed in that form.

• Then how about the first row? – athin Sep 7 '19 at 12:14

In the second row you have paired two and two numbers. 910 is the only chunk where the two numbers paired does not have the same number of digits.