Transcript All numbers divisible by both 4 and 15 are also divisible by which of the following? a) 6 Difficulty: Medium b) 8 c) 18 d)

All numbers divisible by both 4 and 15 are also divisible by which of the following?
a) 6
Difficulty: Medium
b) 8
c) 18
d) 24
e) 45
HIINT
“Divisible by” means that the remainder is zero after the division. For
example, 8 is divisible by 4, but it is not divisible by 3. Think of some
numbers that are divisible by both 4 and 15, and then test these to see if
they are also divisible by the numbers given as answer choices.
A: 6
Explanation:
“Divisible by” means that the remainder is zero after the division. For
example, 8 is divisible by 4, but it is not divisible by 3, since dividing 8 by 3
leaves a remainder of 2.
First, find a number that is divisible by both 4 and 15. One such number is 60.
Now check each choice to see if 60 is divisible by that choice. 60 is divisible
by choice A, but it is not divisible by any of the other choices. Therefore, this
choice, 6, must be the correct answer.
When the arithmetic is simple and you understand what the question is asking,
it’s okay to find the answer by:
checking each choice
eliminating choices
In more complicated problems, however, this can take more time than finding a
solution through mathematical reasoning.