100+ Problems on Numbers with Solutions Pdf - 1

Question: 1

Which one of the following is a prime number?

(A) 143

(B) 221

(C) 343

(D) 823

Ans: C

343 is divisible by 7.

143 is divisible by 11 and 221 is divisible by 13.

Question: 2

A four digit number is divisible by 7 becomes divisible by 3, when 10 is added to it. The largest such number is

(A) 9947

(B) 9987

(C) 9989

(D) 9996

Ans: C

Largest number of four digits is 9999. On dividing 9999 by 7, the remainder comes out to be 3.

Therefore, the largest number of four digits divisible by 7 is 9996. Let 9996 – x + 10 be divisible by 3.

We find that x = 7.

Therefore required number (9996-7) = 9989.

Question: 3

The largest natural number which exactly divides the product of any four consecutive natural numbers is

(A) 6

(B) 12

(C) 24

(D) 120

Ans: C

Required number = 1 x 2 x 3 x 4 = 24.

Question: 4

The unit’s digit in the product 274 x 318 x 577 x 313 is

(A) 2

(B) 3

(C) 4

(D) 5

Ans: A

Required digit = Unit digit in ( 4 x 8 x 7 x 3) = 2.

Question: 5

The difference between the local value and face value of 7 in the numeral 657903 is

(A) 901

(B) 903

(C) 6993

(D) 7896

Ans: C

(Local Value) – (Face Value) = (7000 – 7) = 6993.

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