Challenge Prelims V1.0 – Day 13 – CSAT Paper

1. How many pairs of natural numbers are there such that the difference of whose squares is 63 (UPSC 2020)

(a) 3

(b) 4

(c) 5

(d) 2

2. Which is the smallest number among √10-√3 , √9-√4 , √8-√5 , √7-√6

(a) √10-√3

(b) √9-√4

(c) √8-√5

(d) √7-√6

3. What is the digit at unit place for 356⁴²⁷⁸

(a) 1

(b) 3

(c) 6

(d) 9

4. If a number m x 8³ x 12² x 7⁵ has 11² and 3³ as factors, then what is the minimum value of m

(a) 1089

(b) 363

(c) 248

(d) 1331

5. Sum of digits of a number obtained by the expression 1000ⁿ + m is 2, where m and n are whole numbers. Then which of the following is true?

(a) m will always be 1

(b) The sum of digits of m is 1

(c) Value of m will always be less than 1000

(d) None of the above

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