Natural Number(प्राकृतिक संख्या)

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All the numbers used in counting are called natural numbers.
For example :- 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 …………… ∞
∞ means infinity.

Natural numbers are known by three names.
• Natural numbers
• Enumeration Number
• positive integer number

These numbers are used to count objects.
• There are 5 books on the table.
• There are 1200 students in my school.
• You have 2 cars.

• Natural numbers are denoted by " N ".
• The smallest natural number is " 1 ".
• The largest natural number is " ∞ ".

• Sum of first n natural numbers (S) = n(n+1) / 2
Here n is the total number of natural numbers.  

1 + 2 + 3 +4 +5 +6 + 7 + 8 + 9 +10 + 12 + 13 14 +15 = ?
Solution :- n = 15  योग (S) = n(n + 1) / 2             = 15(15 + 1) / 2             = 240 / 2             = 120 Ans.