One of the types of math questions you will see on the GRE exam are questions related to common multiples. The following example is similar to the types of common multiple questions you can expect to see on the GRE exam.
Problem:
Which of the following are multiples of both 5 and 7?
a. 105
b. 210
c. 150
d. 252
e. 1225
Approach:
Before even getting down to actual business, by inspection we can eliminate option d. How’s that? Any number which is divisible by 5 has 0 or 5 as the unit’s digit.
Now, If we divide each number first with 5 and then with 7, that would be a cumbersome process. A faster approach would be to rather find the numbers which are multiples of 5*7=35.
We can keep multiplying 35 with numbers 1,2,3, 4 etc to get its multiple and hence can find the correct option.
Here’s the video solution: