Number Theory Review

Which of the following are factors of 42.

• 3

• 4

• 7

• 14

• 21

Answer explanation

Factors of 42

1 x 42

2 x 21

3 x 14

6 x 7

What are the missing numbers in the sequence?

2, 3, 5, 7, _____, 13, ______,19, 23

Answer explanation

This is a sequence of prime numbers.

What are the next two numbers in the sequence?

1, 4, 9, 16, 25 , _____, ______.

Answer explanation

This is a sequence of square numbers

6 x 6 = 36

7 x 7 = 49

Which same number will make the calculation correct?

_____ x _____ = 144

Answer explanation

Square root of 144 = 12

What are the missing numbers in the series?

1,8,_____,64,125,_____

Answer explanation

This is a sequence of cubed numbers

3 x 3 x 3 = 27

6 x 6 x 6 = 216

What same number will make the equation correct?

______ x ______ x ______ = 729

• 3

• 9

• 81

• 243

Answer explanation

Cube root of 729 = 9

• 2.0183

• 23.96

• 0.4971

• 1.003

• 720

• 30

• 240

• 4800

• 1898

• 252

• 56

• 28

• 56

• 588

• 168

• 28