divisiblity | MathCelebrity Forum

# divisiblity

1. ### if q is a whole number and q is a prime, and if 20q is divisible by 6, then q could be

A. 2 B. 3 C. 4 D. 5 E. 6 We have 3 conditions that all must be met: Whole number Prime Number 20 * number is divisible by 6 The are all whole numbers One A, B, and D are prime, so we eliminate C and E 20(2) = 40 which is not divisible by 6 - Eliminate Answer A 20(5) = 100 which is not...
2. ### what is the smallest number greater than 400 that is divisible by 9

what is the smallest number greater than 400 that is divisible by 9? 400/9 = 44.4444 Round down to 45. 45 * 9 = 405
3. ### How many of the numbers between 20 and 40 are prime numbers?

How many of the numbers between 20 and 40 are prime numbers? A) 3 B) 4 C) 5 D) 6 E) 7 Recall that a prime number is a number that only has itself and 1 as a divisor. Remove all the evens since the are divisible by 2 (20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40) Remove all the remaining...
4. ### Prove the following statement for non-zero integers a, b, c, If a divides b and b divides c, then a

Prove the following statement for non-zero integers a, b, c, If a divides b and b divides c, then a divides c. If an integer a divides an integer b, then we have: b = ax for some non-zero integer x If an integer b divides an integer c, then we have: c = by for some non-zero integer y Since b...
5. ### list the natural numbers less than 70 that are divisible by 8

list the natural numbers less than 70 that are divisible by 8 Natural numbers are {1, 2, 3, ... We want natural numbers less than 70 which are divisible by 8: 8 * 1 = 8 8 * 2 = 16 8 * 3 = 24 8 * 4 = 32 8 * 5 = 40 8 * 6 = 48 8 * 7 = 56 8 * 8 = 64 Our answer is: {8, 16, 24, 32, 40, 48, 56, 64}
6. ### Divisibility by 11 no calculator shortcuts

2 rules. If either of them passes, then the number is divisible by 11: Sum of the odd digits - Sum of the even digits is divisible by 11 Sum of the odd digits - Sum of the even digits = 0 (Ex. 121)

9. ### the set of natural numbers less than 7 that are divisible by 3

the set of natural numbers less than 7 that are divisible by 3 Natural Numbers less than 7 {1, 2, 3, 4, 5, 6} Only 2 of them are divisible by 3. Divisible means the number is divided evenly, with no remainder: {3, 6}