Properties of Whole Numbers

Summary

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Closure property
Whole numbers are closed under addition and multiplication. Whole numbers are not closed under subtraction and division. If a and b are any two whole numbers, then a+b, axb are also whole numbers.

Commutative property
The sum of two whole numbers is the same, no matter in which order they are added. This is called the commutative property of addition. The product of two whole numbers is the same, no matter in which order they are multiplied. This is called the commutative property of multiplication. Subtraction and division are not commutative in whole numbers. If a and b are any two whole numbers, then a+b = b+a and a×b = b×a.

Additive Identity
A whole number added to '0' remains unchanged. Thus, '0' is called the additive identity in whole numbers. If a is any whole number, then a + 0 = a = 0 + a.

Multiplicative Identity
A whole number multiplied by 1 remains unchanged. Thus, 1 is called the multiplicative identity in whole numbers. If a is any whole number, then a × 1 = a = 1 × a.

Associative property
While adding whole numbers, we can group the numbers in any order. This is called the associative property of addition. While multiplying whole numbers, we can group them in any order. This is called the associative property of multiplication. If a, b and c are any two whole numbers, then (a+b)+c = a+(b+c) and (a×b)×c = a×(b×c).

Distributive property
The product of a whole number with the sum of the two other whole numbers is equal to the sum of the products of the whole number with other two whole numbers. This is called the distributive property of multiplication over addition. If a, b and c are any two whole numbers, then a(b+c) = a×b + a×c.

The product of a whole number with the difference of the two other whole numbers is equal to the difference of the products of the whole number with other two whole numbers. This is called the distributive property of multiplication over subtraction. If a, b and c are any two whole numbers, then a(b–c) = a×b – a×c.

Multiplication by zero
Product of a whole number by zero is equal to zero. If a is any whole number, then a × 0 = 0 = 0 × a.

Division by zero
Division of a whole number by 0 is not defined. If a is any whole number, then a ÷ 0 is not defined.

If a is any whole number, then a ÷ 1 = a.
If a is any non-zero whole number, then a ÷ a = 1.
If a is any non-zero whole number, then 0 ÷ a = 0.

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1 . FIND THE GREATEST NUMBER OF FIVE DIGITS THAT IS EXACTLY DICISIBLE BY 9, 12, 15, 18 AND 24?

Sol:
LCM of 9, 12, 15, 18 and 24 by division method is 360.
Largest number of five digits = 99999
The quotient when...

2 . The traffic lights at three different road crossing change

Here we have to find LCM of 72, 108 and 132
LCM of 72, 108, 132 = 2376
To convert 2376 sec into min, we get
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3 . The HCF & LCM of two numbers are 13 and 1989 respectively.

hcfXlcm=aXb
hcf=13,lcm=1989, a=17
b=(13*1989)/17
b=221
other number is 221

4 . Sample paper SA 1

SA 1 sample papers:

How many centimetres are there in 5 kilometres?
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5 . Sample question paper for SA1

Please go through the SA 1 sample question papers from the following link:
...

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