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Aptitude Number System Practice Q&A - Easy

1225.Which least number when added to 2000 makes it exactly divisible by 19?
7
11
14
17
Explanation:
Now we have given the number 2000.
Dividing it by 19, we get:
2000 = 105 x 19 + 5
Then:
19 - 5
14
So if we 14 added in 2000, then 2014 will be exactly divided by 19.
So the least number that must be added will be 14.
1318.1/4 of a number subtracted from 1/3 of the number gives 12. The Number is
300
410
144
157
Explanation:
Let the number be x
1/4 of the number = 1/4(x) =x/4
1/3 of the number = 1/3(x) =x/3
1/4 of a number subtracted from 1/3 of the number gives 12.
x/3-x/4 =12
x/3×4/4 - x/4×3/3 =12
4x/12 - 3x/12 =12
(4x-3x)/12=12
4x-3x=12×12
x=144
Therefore,the number is 144.
Three fifth of one fourth of a number is 90. The number is?
Solution:
Let the number be y
Three fifth of one fourth of a number is 90.
⇒ 3/5 x 1/4 x y = 90
Evaluate LHS:
⇒3/20 y = 90
Multiply both sides by 20:
⇒ 3y = 1800
Divide both sides by 3:
⇒ y = 600
The number is 600.
1331.The least square number which is divisible by 6, 8 and 15 is:
3400
2500
3600
3000
Explanation:

The least number divisible by 6, 8 and 15
is their L.C.M. which is 120
Now 120 = 2x2x2x3x5
To make it a perfect square, it must be
multiplied by 2x3x5
Required Number=120x2x3x5=3600
1332.Find the least number which when divided
separately by 15, 20, 36 and 48 leaves 3 as remainder
in each case.
723
721
720
689
Explanation:

Required number
= L.C.M. of (15,20,36 and 48) +3
= 720 + 3 = 723
2629.The smallest 3 digit prime number is:
101
103
109
113
Explanation:

The smallest 3-digit number is 100, which is divisible by 2.

$\therefore$ 100 is not a prime number.

$ \sqrt{101} $ < 11 and 101 is not divisible by any of the prime numbers 2, 3, 5, 7, 11.

$\therefore$101 is a prime number.

Hence 101 is the smallest 3-digit prime number.

2630.Which one of the following numbers is exactly divisible by 11?
235641
245642
315624
415624
Explanation:

(4 + 5 + 2) - (1 + 6 + 3) = 1, not divisible by 11.

(2 + 6 + 4) - (4 + 5 + 2) = 1, not divisible by 11.

(4 + 6 + 1) - (2 + 5 + 3) = 1, not divisible by 11.

(4 + 6 + 1) - (2 + 5 + 4) = 0, So, 415624 is divisible by 11.

2631.(?) - 19657 - 33994 = 9999
63650
53760
59640
61560
Explanation:

19657+33994=53651

let $x$ - 53651 = 9999

Then, $x$ = 9999 + 53651 = 63650

2634.$\dfrac{753 \times 753 + 247 \times 247 - 753 \times 247}{753 \times 753 \times 753 + 247 \times 247 \times 247}$=?
$ \dfrac{1}{1000} $
$ \dfrac{1}{506} $
$ \dfrac{253}{500} $
None of these
Explanation:

Given Exp. =$ \dfrac{(a^2 + b^2 - ab)}{(a^3 + b^3)} = \dfrac{1}{(a + b)} = \dfrac{1}{(753 + 247)} = \dfrac{1}{1000} $

2635.(?) + 3699 + 1985 - 2047 = 31111
34748
27474
30154
27574
Explanation:

$ x $ + 3699 + 1985 - 2047 = 31111

$\Rightarrow$   $ x $ + 3699 + 1985 = 31111 + 2047

$\Rightarrow$   $ x $ + 5684 = 33158

$\Rightarrow$   $ x $ = 33158 - 5684 = 27474.

2641.107 x 107 + 93 x 93 = ?
19578
19418
20098
21908
Explanation:

107 x 107 + 93 x 93= (107)2 + (93)2

= (100 + 7)2 + (100 - 7)2

= 2 x [(100)2 + 72]   [Ref: (a + b)2 + (a - b)2 = 2(a2 + b2)]

= 20098

2646.How many of the following numbers are divisible by 3 but not by 9 ?
2133, 2343, 3474, 4131, 5286, 5340, 6336, 7347, 8115, 9276
5
6
7
None of these
Explanation:

Marking $\left(/\right)$ those which are are divisible by 3 by not by 9 and the others by $\left(X\right) $, by taking the sum of digits, we get:s

2133 $\rightarrow$ 9 $\left(X\right) $

2343 $\rightarrow$ 12 $\left(/\right)$

3474 $\rightarrow$ 18 $\left(X\right) $

4131 $\rightarrow$ 9 $\left(X\right) $

5286 $\rightarrow$ 21 $\left(/\right)$

5340 $\rightarrow$ 12 $\left(/\right)$

6336 $\rightarrow$ 18 $\left(X\right) $

7347 $\rightarrow$ 21 $\left(/\right)$

8115 $\rightarrow$ 15$\left(/\right)$

9276 $\rightarrow$ 24 $\left(/\right)$

Required number of numbers = 6.

2647.$\dfrac{(963 + 476)^2 + (963 - 476)^2}{(963 \times 963 + 476 \times 476)}$=?
1449
497
2
4
Explanation:
Given Exp. = $ \dfrac{(a + b)^2 + (a - b)^2}{(a^2 + b^2)}$ = $\dfrac{2(a^2 + b^2)}{(a^2 + b^2)} $= 2
2650.8597 - ? = 7429 - 4358
5426
5706
5526
5476
Explanation:

 7429         Let 8597 - x = 3071

-4358         Then, x = 8597 - 3071

 -------        = 5526

  3071

 -------

2651.The smallest prime number is:
1
2
3
4
Explanation:

The smallest prime number is 2.

2652.12345679 x 72 = ?
88888888
888888888
898989898
9999999998
Explanation:

12345679 x 72= 12345679 x (70 +2)

= 12345679 x 70 + 12345679 x 2

= 864197530 + 24691358

= 888888888

2655.Which one of the following is the common factor of (4743 + 4343) and (4747 + 4347) ?
(47 - 43)
(47 + 43)
(4743 + 4343)
None of these
Explanation:

When $ n $ is odd, ( x $ n $ + $ a $$ n $) is always divisible by $ x $ + $ a $.

$\therefore$Each one of 4743 + 4343 and 4747 + 4347 is divisible by 47 + 43.

2656.-84 x 29 + 365 = ?
2436
2801
-2801
-2071
Explanation:

Given Exp.= -84 x $\left(30 - 1\right)$ + 365= -$\left(84 \times 30\right)$ + 84 + 365= -2520 + 449= -2071

2659.In a division sum, the divisor is 10 times the quotient and 5 times the remainder. If the remainder is 46, what is the dividend ?
4236
4306
4336
5336
Explanation:

Divisor = 5 x 46 = 230

$\therefore$ 10 x Quotient = 230    $\Rightarrow$ =$ \dfrac{230}{10} $= 23

Dividend = [Divisor x Quotient] + Remainder

    = [230 x 23] + 46

    = 5290 + 46

    = 5336.

2660.4500 x ? = 3375
$ \dfrac{2}{5} $
$ \dfrac{3}{4} $
$ \dfrac{1}{4} $
$ \dfrac{3}{5} $
Explanation:

4500 x $ x $ = 3375   $\Rightarrow$   $ x$ =$\dfrac{3375}{4500}$=$ \dfrac{75}{100} $=$ \dfrac{3}{4} $

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