Interactive number line for integers, fractions, decimals, and irrationals. Plot intervals, inequalities, and absolute values.
Place integers, fractions, decimals, irrational values, intervals, and inequality solutions on a number line. Individual values appear as points, while sets appear as segments or rays. Endpoint markers distinguish included boundaries from excluded ones, making interval notation easier to interpret visually. The detail most often misread is endpoint inclusion: a filled endpoint belongs to the set, but an open endpoint does not, even when the highlighted region reaches that boundary.
A concrete input and expected output from the current implementation.
Input
-2 <= x < 3
Expected output
A highlighted segment from -2 to 3, with a filled endpoint at -2 and an open endpoint at 3. In interval notation, the set is [-2, 3).
The <= relation includes -2, so the left endpoint is filled. The strict < relation excludes 3, so the right endpoint is open; every number between those boundaries satisfies both conditions.
A single number is positioned according to its order relative to zero: negative values lie to the left and positive values to the right. Equivalent fractions and decimals occupy the same coordinate, so 1/2 and 0.5 identify one location. When an irrational value is plotted, its screen position is necessarily a finite visual approximation of that exact number.
An interval highlights the portion of the line belonging to the set. A closed endpoint marks an included boundary, while an open endpoint marks an excluded boundary. A ray represents a one-sided unbounded inequality. For absolute-value conditions, the plotted region represents distance from a center: less-than conditions select nearby points, while greater-than conditions select points outside the boundary distances.
No. They are different notations for the same real number, so both correspond to the same coordinate. A label may preserve the entered representation, but that does not change the plotted value. The same principle applies to equivalent forms such as 0.25, 1/4, and 25/100.
No. Infinity and negative infinity describe unbounded directions, not real numbers that can be included in a set. An unbounded interval therefore continues as a ray rather than ending at a filled infinity point. In interval notation, parentheses are used beside infinity, as in [2, infinity).
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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