← 📐 Mathematics · usually met in Std 6-12
Natural, whole, integer, rational, irrational, real — each invented because the one before it could not answer a question somebody had.
Counting numbers came first. Zero and negatives were needed for debts and for place value. Fractions answered division that did not come out even. Then the Greeks found that the diagonal of a unit square cannot be written as any fraction at all — the square root of two is irrational — and the number line turned out to be far more crowded than anyone had assumed. Rationals and irrationals together make the reals.
Zero deserves its own mention. As a placeholder and as a number in its own right, with rules for arithmetic, it was developed in India, and Brahmagupta wrote down rules for working with zero and negative numbers in the seventh century. The decimal place-value system travelled from India through the Arab world to Europe, which is why the digits are called Hindu-Arabic numerals.
Want to see it moving? Search YouTube for “Number systems” ↗ — we send you to the search rather than to one video, because a link to one video eventually rots.
This entry was written for Star Student in our own words — it is a summary, not a source. Here is where the people who actually hold these facts keep them. Go and check.
Your own textbook ↗Balbharati publishes the textbooks free to read online. Your chapter is the thing to check first — an encyclopedia is a summary, and the syllabus is the syllabus.Last gone through: 1 October 2026 · How these entries are written
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