Remainders

Based on our last discussion of remainders, let’s start with a frequently asked question type on the GMAT.

Many GMAT questions could have a piece of information like

“When positive integer n is divided by 5, the remainder is 1.”

To use this information, you must find the different possible values of n. To find the different possible values of n, we shall use the relationship between dividend, divisor, quotient, and remainder that we discussed in the previous post.

Dividend = Quotient x Divisor + Remainder

All we have to do to generate possible values of n is perform two calculations

– multiply 5 by an integer

– add 1 to that product

In doing so, we get the following table.

Notice that possible values of n follow a pattern: each next value of n is 5 more than the previous value. So we can also generate the values of n by adding 5 at each step, and hence the different values of n form an arithmetic sequence.

As you can see, infinite values of n will satisfy the given condition. So, you will have to practice such questions to get an idea of the most relevant values of n.

Consider the following example –

Question – A positive integer n leaves a remainder of 4 after division by 6 and a remainder of 3 after division by 5. What is the remainder that n leaves after division by 30?

1. 1. 3 b. 10 c. 15 d. 20 e. 28

Solution – From the first condition, n could be 4,10,16,22,28,..

From the second condition, n could be 3,8,13,18,23,28,..

We want values of n that satisfy both conditions; hence, the first possible value of n is 28. And when we divide 28 by 30, the remainder is 28. Answer (e)

Here’s another similar question –

When positive integer x is divided by 5, the remainder is 2. When positive integer

y is divided by 4; the remainder is 1. Which of the following values CAN NOT be the

sum x+y?

1. 1. 12 b. 13 c. 14 d. 16 e. 21

Answer. C

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