Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 15

EASY

IOQM - PRMO and RMO

IMPORTANT

Earn 100

What is the largest possible prime value of $n^{2} - 12 n + 27,$ where $n$ ranges over all positive integers?

66.67% studentsanswered this correctly

Important Questions on Number System

MEDIUM

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 17

Let

A

be the set of positive integers that have no prime factors other than

2, 3

or

5

. The infinite sum

\frac{1}{1} + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + \frac{1}{8} + \frac{1}{9} + \frac{1}{10} + \frac{1}{12} + \frac{1}{15} + \frac{1}{16} + \frac{1}{18} + \frac{1}{20} + \dots . .

of the reciprocals of the elements of

A

can be expressed as

\frac{m}{n},

where

m

and

n

are relatively prime positive integers. What is

m + n ?

HARD

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 18

For some positive integer

n

, the number

110 n^{3}

has

110

positive integer divisors, including

1

and the number

110 n^{3}

. The number

81 n^{4}

have

D

positive integer divisors. What is

(\frac{D}{5}) ?

MEDIUM

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 19

What is the minimum number of digits to the right of the decimal point needed to express the fraction

\frac{123456789}{2^{26} \cdot 5^{4}}

as a decimal?

HARD

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 20

How many positive two-digit integers are factors of

2^{24} - 1

?

HARD

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 21

Let

N

be the positive integer for which the sum of its two smallest factors is

4

and the sum of its two largest factors is

204

. The value of

(\frac{N}{3})

is

HARD

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 22

Let

S = {1, 2, 3, \dots, 20}

be the set of all positive integers from

1

to

20

. Suppose that

N

is the smallest positive integer such that exactly eighteen numbers from

S

are factors of

N

, and the only two numbers from

S

that are not factors of

N

are consecutive integers. Find the sum of the digits of

N

.

HARD

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 23

m

and

n

are two positive integers of reverse order (for example,

123

and

321

) such that

m n = 1446921630

. Now the value of

m + n

is given as

a b 4 b a

. Find the product of

a

and

b

MEDIUM

IOQM - PRMO and RMO

IMPORTANT

Non-Routine Mathematics Resource Book-1 for PRMO>Chapter 2 - Number System>EXERCISE - 2.1>Q 24

Find the number of positive divisors of

{(2008^{3} + (3 \times 2008 \times 2009) + 1)}^{2}