Prime numbers

The Maths Habit

  1. List all the factors of 30.

    1, 2, 3, 5, 6, 10, 15, 30

  2. List all the factors of 63.

    1, 3, 7, 9, 21, 63

  3. List all the factors of 100.

    1, 2, 4, 5, 10, 20, 25, 50, 100

The biggest prime found so far.
How many digits long is it?

More than 41 million

Factor
A number that divides exactly into another number.
Prime number
A number with exactly two factors: 1 and itself.

79 1, 71, 3, 9

Is it a prime number?

23

Is it a prime number?

27

Is it a prime number?

31
Factor pairs
1×31= 31
×= 31
×= 31
Factors1, 31
How many factors?2
Prime?YesNo

Is it a prime number?

39
Factor pairs
1×39= 39
3×13= 39
×= 39
Factors1, 3, 13, 39
How many factors?4
Prime?YesNo

Is it a prime number?

31
Factor pairs
1×31= 31
×= 31
×= 31
Factors1, 31
How many factors?2
Prime?YesNo

Is it a prime number?

37
Factor pairs
1×37= 37
×= 37
×= 37
Factors1, 37
How many factors?2
Prime?YesNo

Is it a prime number?

31
Factor pairs
1×31= 31
×= 31
×= 31
Factors1, 31
How many factors?2
Prime?YesNo

Is it a prime number?

51
Factor pairs
1×51= 51
3×17= 51
×= 51
Factors1, 3, 17, 51
How many factors?4
Prime?YesNo

Is it a prime number?

31
Factor pairs
1×31= 31
×= 31
×= 31
Factors1, 31
How many factors?2
Prime?YesNo

Is it a prime number?

43
Factor pairs
1×43= 43
×= 43
×= 43
Factors1, 43
How many factors?2
Prime?YesNo

Is it a prime number?

31
Factor pairs
1×31= 31
×= 31
×= 31
Factors1, 31
How many factors?2
Prime?YesNo

Is it a prime number?

49
Factor pairs
1×49= 49
7×7= 49
×= 49
Factors1, 7, 49
How many factors?3
Prime?YesNo

Prime numbers: is it prime? worksheet, page 1

Prime numbers: is it prime? worksheet, page 2

Answer sheet

  1. Which is the only even prime number? Why are there no others?

    2

  2. Find two prime numbers that add up to 30.

    13 and 17, for example

  1. Is 53 a prime number? Give a reason.

    Yes: factors 1 and 53

  2. Is 57 a prime number? Give a reason.

    No: 57 = 3 × 19

  3. List the prime numbers between 30 and 50.

    31, 37, 41, 43, 47
Exit tickets to print