What are prime and composite numbers in maths?
A prime number is a whole number greater than 1 that can only be evenly divided by 1 and itself.
Examples: 2, 3, 5, 7, 11,... are prime numbers. If you try to divide them by numbers other than 1 or themselves, the remainder will not be zero.
A composite number is a whole number greater than 1 that can be evenly divided by 1, itself and other numbers.
Examples: 4, 6, 8,12..are composite numbers because:
4÷2 = 2 , 4 is divisible by 1, itself and 2
6÷2 = 3 , 6÷3 = 2 , 6 is divisible by 1, itself, 2 and 3.
8÷2 = 4 , 8÷4 = 2 , 8 is divisible by 1, itself, 2 and 4.
12÷2 = 6 , 12÷3 = 4 , 12÷4 = 3 , 12÷6 = 2 , 12 is divisible by 1, itself, 2, 3, 4 and 6.
Answer the following Questions on Prime and Composite Numbers.

Which of the following numbers are prime?
1, 6.3, 11, 14, 13, 21, 23, 4/5, 100, 123 .

Which of the following numbers are composite?
1, 8.4, 15, 13, 9/2, 24, 33.

List all prime numbers between 30 and 50 inclusive.

List all composite numbers between 100 and 110 inclusive.

Is the sum of two prime numbers always a prime number?

Is the product of two prime numbers also a prime number?

Which is the largest 3 digit prime number?

Which is the smallest 2 digit prime number?

List all the two digit prime numbers that can be made from the digits 1, 3 and 6 (used only once each).

Can you find a prime number whose least significant digit (digit on the right) is 0?

Can you find a prime number whose least significant digit (digit on the right) is 5?

Can you find a prime number such that the sum of all its digits is equal to 12?
Detailed Solutions and explanations are included.
