Number Theory

Which number is prime?

• 51

• 53

• 55

• 57

Which number is composite?

• 11

• 21

• 31

• 41

The least common multiple (LCM) of 10 and 25 is:

• 50

• 75

• 100

• 250

The factors of 40 are

• {1,2,3,4,5,6,8,10,20,40}

• {1,2,4,5,6,8,10,20,40}

• 1,2,4,5,8,10,20,40}

• {1,2,4,5,8,10,40}

Which of these are prime numbers?

(Select more than one answer)

• 23

• 111

• 3

• 41

Which of these are composite numbers?

(More than one answer)

• 9

• 49

• 107

• 2

Which number is divisible by 5?

• 3,214

• 3,240

• 4,506

• 5,206

Which number is divisible by 3?

• 3,403

• 2,986

• 8,217

• 5,009

What number is prime?

• 31

• 33

• 35

• 39

Which number is composite?

• 71

• 73

• 77

• 79