Natural number
- CBSE · NCERT Class 6, Ch 1 Patterns in Mathematics
- CBSE · NCERT Class 9, Ch 3 The World of Numbers
A natural number is one of the counting numbers 1, 2, 3, 4 and so on, the numbers you use to count things.
Natural numbers start at 1 and never end. There is no largest one, because you can always add 1 more. Zero is not a natural number. Put zero in front of the list and you get the whole numbers.
NCERT's Class 6 book calls them counting numbers. The Class 9 book uses the name natural numbers, where it builds up the whole family of numbers step by step.
A small example
Look at the list -3, 0, 2.5, 7 and 12. Only 7 and 12 are natural numbers. -3 is negative, 0 is zero, and 2.5 is not a whole count.
Add two natural numbers and the answer is always a natural number: 7 + 12 = 19. Subtraction is different. 7 - 12 = -5, and -5 is not a natural number. That gap is one reason integers were needed.
Why it matters later
Class 10 Chapter 1, Real Numbers, is full of statements about natural numbers. The fundamental theorem of arithmetic is about breaking them into primes. One worked example asks whether 4ⁿ can end in 0, where n is a natural number. Knowing exactly which numbers n can be is the first step of that answer.
Sources
Facts last checked against these sources on 30 September 2026.
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