# CAT Number System Questions for Practice

Question 1:
In some code, letters a, b, c, d and e represent numbers 2, 4, 5, 6 and 10. We just do not know which letter represents which number. Consider the following relationships:

a + c = e,

b – d = d and

e + a = b

Which of the following statements is true?

Topic: Basics

[1] b = 4, d = 2
[2] a = 4, e = 6
[3] b = 6, e = 2
[4] a = 4, c = 6

Question 2:
A change-making machine contains one-rupee, two-rupee and five-rupee coins. The total number of coins is 300. The amount is Rs. 960. If the numbers of one-rupee coins and two-rupee coins are interchanged, the value comes down by Rs. 40. The total number of five-rupee coins is
Topic: Basics

[1] 100
[2] 140
[3] 60
[4] 150

Question 3:
Number S is obtained by squaring the sum of digits of a two-digit number D. If difference between S and D is 27, then the two-digit number D is
Topic: Digits

[1] 24
[2] 54
[3] 34
[4] 45

Question 4:
The nth element of a series is represented as

Xn= (–1)nXn–1

If X0= x and x > 0, then which of the following is always true?

Topic: Basics

[1] Xnis positive if n is even
[2] Xnis positive if n is odd
[3] Xnis negative if n is even
[4] None of these