Even Numbers: Any number that can be divided by 2 is called Even Number. Even numbers end with 0,2,4,6 or 8.

Example:12, 468, 896, 30, 654, 114

Odd Numbers: Any number that cannot be divided by 2 is called Odd Number. Odd numbers end with 1,3,5,7 or 9.

Example: 3, 17,451, 759, 35, 873

Prime Numbers: A number that can only be divided by 1 and itself.

Example: 2,3,5,7,11,13,17,19,23,29,31,37,41,43

• 1 is not a prime number.
• Smallest prime number is 2

Face Value of a digit: The face value of a number is its own exact value.

Place value of a digit: Local value of a digit is the value a digit holds in a number.

Example: In number 5823, Face value of 5 = 5, 8 = 8, 2 = 2, and 3 = 3.

And the Place value of 5=5000, 8=800, 2=20 and 3=3

Numbers Divisible by 2: Any number which ends with 0,2,4,6 or 8 is divisible by 2

For example:

• 45698: This number ends with 8 that is why it is divisible by 2
• 398564: This number ends with 4 that is why it is divisible by 2
• 980230: This number ends with 0 that is why it is divisible by 2
• 26: This number ends with 6 that is why it is divisible by 2
• 562: This number ends with 2 that is why it is divisible by 2

Numbers Divisible by 3:If the sum of the digits of a number is divisible by 3, then that whole number is divisible by 3.

For example:

• 75684: The sum of its digits is (7+5+6+8+4=30). And 30 is divisible by 3. It means the full number 75684 is divisible by 3.

• 75683:The sum of its digits is (7+5+6+8+3=29). And 29 is not divisible by 3. It means the full number 75683 is not divisible by 3.

Numbers Divisible by 5:If the last digit of a number is either 0 or 5, then that number is divisible by 5.

For example:

• 75680: The last digit is 0, that is why 75680 is divisible by 5.
• 985: The last digit is 5, that is why 985 is divisible by 5.
• 63584: The last digit is 4, that is why 63584 is not divisible by 5.

Exercise for Number System

Example1. Write the number 65289 in words.

Answer: Sixty five thousand two hundred eighty nine.

Example2. Write the number 538945 in words.

Answer: Five lakhs thirty eight thousand nine hundred forty five

Example3. Write the number 29503 in words

Answer: Twenty nine thousand five hundred three

Example4. Write the number 900124 in words

Answer: Nine lakhs one hundred twenty four

Example5. What is the face value of digit “5” in number 704532?

Answer: Face value of digit “5” is 5.

Example6. What is the place value of digit “6” in number 963098?

Answer: Place value of digit “6” is 60000.

Example7. What is the place value of digit “3” in number 5623?

Answer: Place value of digit “3” is 3.

Example8. What is the face value of digit “9” in number 209536?

Answer: Face value of digit “9” is 9.

Example9. What is the place value of digit “4” in number 4623?

Answer: Place value of digit “4” is 4000.

Example10.What is the difference between Place value and Face value of digit “7” in number 867943?

Answer: Place value of “7” = 7000

Face value of “7” = 7

Difference = 7000-7 = 6993

Example11.What is the difference between Place values of digit “9” and “3” in number 689235?

Answer: Place value of “9” = 9000

Place value of “3” = 30

Difference = 9000-30 = 8970

Example12.What is the smallest Prime Number?

Answer: 2

Example13. Is number 5632 divisible by 2?

Answer: Yes.

Its last number is 2. That is why it is divisible by 2.

Example14. Is number 2359 divisible by 2?

Answer: No

Its last number is 9, which is not divisible by 2.

Example15. Is number 6532 divisible by 3?

Answer: No.

6+5+3+2=16. As 16 is not divisible by 3, the number is not divisible by 3.

Example16.Is number 210432 divisible by 3?

Answer: Yes

2+1+0+4+3+2=12. As 12 is divisible by 3, the number is divisible by 3.

Example17.Is number 698535 divisible by 5?

Answer: Yes

The last digit of number is 5, that is why it is divisible by 5.

Example18. Is number 645741 divisible by 5?

Answer: No

The last digit is 1, that is why it is not divisible by 5.

Example19. How much we should add to 1256, so that it becomes divisible by 3?

Answer: 2

1+2+5+6=13, 13 is not divisible. If we add 2, then 15 will be divisible by 3.

Example20. How much we should subtract from 62351 so that it becomes divisible by 3?

Answer: 2

6+2+3+5+1=17. 17 is not divisible. If we subtract 2, then 15 will be divisible by 3.

Example21.If a number 25y513 is divisible by 3, then what is the value of y?

Answer: for a number to be divisible by 3, sum of its digits should be divisible by 3.

2+5+y+5+1+3 = Should be divisible by 3

2+5+5+1+3=16

16 is not divisible by 3, but 18 is divisible.

Hence, 2+5+y+5+1+3 =18

So, y=2