Numbers Questions

Q:

On dividing 4150 by a certain number , the quotient is 55 and the remainder is 25, the divisor is

Divisor = $\inline \fn_jvn \left [ \frac{Divided-Remainder}{Quotient} \right ]$

= $\inline \fn_jvn \frac{45\times 46}{2}=75$

2149
Q:

A boy multiplied 987 by a certain number and obtained 559981 as his answer. If in the answer both 98 are wrong and the other digits are correct , then the correct answer would be :

 A) 553681 B) 555181 C) 555681 D) 556581

Explanation:

987 = 3 * 7 * 47.
So, the required number must be divisible by each one of 3, 7, 47
553681 => (Sum of digits = 28, not divisible by 3)
555181 => (Sum of digits = 25, not divisible by 3)
555681 is divisible by each one of 3, 7, 47.

4 2125
Q:

How many of the following numbers are divisible by 132?

264,396,462,792,968,2178,5184,6336

 A) 4 B) 5 C) 6 D) 7

Explanation:

132 = 4 x 3 x 11, So if the number is divisible by all three numbers 4,3 and 11,then the number is divisible by 132 also.
264   => 4,3,11(/)
396   => 4,3,11(/)
462   => 11,3
792   => 4,3,11(/)
968   => 11,4
2178 => 11,3
5184 => 3,4
6336 => 4,3,11(/)
Required number of numbers=4.

7 2079
Q:

How many terms are in the G.P. 3, 6, 12, 24, ......., 384 ?

 A) 8 B) 9 C) 10 D) 11

Explanation:

Here a = 3 and r = 6/3 = 2. Let the number of terms be n.
Then, t = 384 => a * r^(n-1) = 384
=> 3 * 2^(n-1) = 384 => 2^(n-1) = 128 = 2^(7)

=> n-1 = 7 => n = 8.

5 1970
Q:

The sum of the two numbers is 12 and their product is 35.What is the sum of the reciprocals of these numbers?

 A) 12/35 B) 1/35 C) 35/8 D) 7/32

$\inline \fn_cm \frac{a+b}{ab}=\frac{12}{35}$
$\inline \fn_cm \frac{1}{b}+\frac{1}{a}=\frac{12}{35}$