Question

Find the digit that is not written in the same font as others. 

Hint:

In visual discrimination tasks, pay close attention to subtle details like line thickness, curvature, and the presence or absence of serifs. Systematically compare each item to a mental "baseline" established by the majority of the items.

Answer 1

1. 0, 1, 2, 3, 4, 6, 7, 8, 9: Each of these digits is drawn with a plain, even stroke width and square-cut ends, with no small extra marks where a stroke terminates. They all belong to the same sans-serif style.
2. 5: This digit carries a small serif, a short extra stroke, at the top bar and at the foot of its lower curve, and its stroke width is not as even as the rest. It is drawn in a different, serif-influenced style.

Since every digit except 5 shares the same plain stroke style, and 5 is the only one carrying serifs, 5 is the digit written in a different font.

So the correct answer is 5.

Answer 2

A third way to check is to look at how each digit was likely built, since fonts differ in whether their digits are made from geometric circles and straight lines, or from calligraphic curves with varying thickness.

Most of the digits shown look like they are built from simple circular bowls and straight strokes of one constant thickness, the kind of shape you would get from a basic geometric, sans-serif design.

The digit 5 does not match this construction. Its curve thickens and thins along its length, and small serif feet finish off its top bar, both signs of a calligraphic, serif-based design rather than a geometric one.

Because this construction style is different from every other digit shown, 5 is the odd one out. So the correct answer is 5.