Number Properties

Question 1

Even - even

Answer 1

Even

Question 2

Even - odd

Answer 2

Odd

Question 3

Odd - odd

Answer 3

Even

Question 4

Odd - even

Answer 4

Odd

Question 5

Even + even

Answer 5

Even

Question 6

Even + odd

Answer 6

Odd

Question 7

Odd + even

Answer 7

Odd

Question 8

Odd + odd

Answer 8

Even

Question 9

Even x even

Answer 9

Even

Question 10

Even x odd

Answer 10

Even

Question 11

Odd x odd

Answer 11

Odd

Question 12

Even/even

Answer 12

Even or odd

Question 13

Even / odd

Answer 13

Even

Question 14

Odd / odd

Answer 14

Odd

Question 15

Prime numbers < 100

Answer 15

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97

Question 16

Formula for a x b

Answer 16

LCM (a,b) x GCF (a,b)

Question 17

Divisibility rule for 3

Answer 17

Sum of all digits is divisible by 3

Question 18

Divisibility rule for 4

Answer 18

Last 2 digits are divisible by 4 or is a multiple of 100

Question 19

Divisibility rule for 6

Answer 19

Even and sum of digits is a multiple of 3

Question 20

Divisibility rule for 8

Answer 20

Even and last 3 digits are divisible by 8, or multiples of 1000

Question 21

Divisibility rule for 9

Answer 21

Sum of all digits is divisible by 9

Question 22

Divisibility rule for 11

Answer 22

Sum of odd numbered place digits - sum of even place digits is divisible by 11

Question 23

Divisibility rule for 12

Answer 23

Divisible by 3 (sum of all digits divisible by 3) and 4 (last 2 digits divisible by 4 or multiple of 100)

Question 24

X(x+1)(x-1) is divisible by

Answer 24

3!

Question 25

Product of x consecutive integers is divisible by

Answer 25

X!

Question 26

N^5 - 5n^5 + 4n

Answer 26

5 consecutive integers from (n-2) to (n+2), divisible by 120!

Question 27

If n is odd, (n-1)(n+1) is divisible by

Answer 27

8

Question 28

Formula for division and remainders

Answer 28

X/y = Q + r/y

Question 29

Trailing zeros

Answer 29

5x2 pairs of prime factorization

Question 30

Units digit of any factorial > or equal to 5!

Answer 30

0 (5x2 pair)

Question 31

Leading zeros if 0

Answer 31

0

Question 32

Leading zeros of 10

Answer 32

1

Question 33

Leading zeros if 100

Answer 33

2

Question 34

Formula to find leading zeros

Answer 34

If x is an integer with k digits, 1/x will have k-1 leading zeros

Unless x is perfect power of 10, then k-2 leading zeros

Question 35

Leading zero definition

Answer 35

Zeros to the right of decimal but before first nonzero number

Question 36

How to know if a decimal terminates

Answer 36

Prime factorization of fraction denominator contains only 2s, 5s, or both

Question 37

Unit digit pattern of consecutive powers of 2

Answer 37

2,4,8,6

Question 38

Unit digit pattern of consecutive powers of 3

Answer 38

3,9,7,1

Question 39

Unit digit pattern of consecutive powers of 4

Answer 39

4,6

Question 40

Unit digit pattern of powers of 5

Answer 40

All end in 5

Question 41

Unit digit pattern of powers of 6

Answer 41

All end in 6

Question 42

Unit digit pattern of consecutive powers of 7

Answer 42

7,9,3,1

Question 43

Unit digit pattern of consecutive powers of 8

Answer 43

8,4,2,6

Question 44

Unit digit pattern of consecutive powers of 9

Answer 44

9,1