EXERCISE-3F
Mark $(\checkmark)$ against the correct answer in each of the following :
Question 1
Q.1. The smallest whole number is
(a) 1
(b) 0
(c) 2
(d) none of these
Ans. The smallest whole number is 0
Question 2
Q.2. The least number of 4 digits which is exactly divisible by 9 is
(a) 1018
(b) 1026
(c) 1009
(d) 1008
Ans. The least 4-digit number $=1000$
On dividing 1000 by 9 , we get
Remainder $=1$
<division to be added>
$\therefore$ Least 4-digit number which is
Divisible by $9=1000-1+9$
$=1000+8=1008$
Question 3
Q.3. The largest number of 6 digits which is exactly divisible by 16 is
(a) 999980
(b) 999982
(c) 999984
(d) 999964
Ans.
The largest 6-digit number $=999999$
On dividing by 16 , we get
Remainder $=15$
<division to be added>
The greatest 6-digit number divisible by 16
$=999999-15=999984$
Question 4
Q.4. What least number should be subtracted from 10004 to get a number exactly divisible by 12 ?
(a) 4
(b) 6
(c) 8
(d) 20
Ans.
On dividing 10004 by 12 , we get
$\text { remainder }=8$
<division to be added>
$\therefore 8$ is to be subtracted from 10004
Question 5
Q.5. What least number should be added to 10056 to get a number exactly divisible by 23 ?
(a) 5
(b) 18
(c) 13
(d) 10
Ans.
On dividing 10056 by 23
We get remainder $=12$
<division to be added>
$\therefore$ The least number to be added
$=23-5=18$
Question 6
Q.6. What whole number is nearest to 457 which is divisible by 11 ?
(a) 450
(b) 451
(c) 460
(d) 462
Ans.
On dividing 457 by 11
We get remainder $=6$
<division to be added>
Which is greater than half of 11
$\therefore$ The number nearest to 457 which is divisible 11 will be $=457-6+11=457+5=462$
Question 7
(a) 185
(b) 186
(c) 184
(d) none of these
Ans. Whole number between 1018 and 1203 are 1019 to 1202 are 1202 - 1018
$=184$
Question 8
(a) 491
(b) 521
(c) 701
(d) 679
Ans. Divisor $=46$
Quotient = 11
Remainder $=15$
$\therefore$ Number $=$ Divisor $\times$ Quotient + Remainder
$=46 \times 11+15=506+15=521$
Question 9
(a) 11
(b) 23
(c) 12
(d) none of these
Ans.
Dividend = 199
Quotient = 16
Remainder $=7$
$\therefore \text { Divisor }=\frac{199-7}{16}=\frac{192}{16}=12$
Question 10
(a) 11023
(b) 4245
(c) 4155
(d) none of these
Ans.
$\begin{aligned} & 7589-?=3434 \\ & \therefore \text { Required number }=7589-3434 \\ & =4155 \end{aligned}$
Question 11
(a) 57213
(b) 58513
(c) 58113
(d) 56413
$\begin{aligned} & \text { Ans. } 587 \times 99=587 \times(100-1) \\ & =587 \times 100-587 \times 1 \\ & =58700-587=58113 \end{aligned}$
Question 12
(a) 32280
(b) 26900
(c) 53800
(d) 10760
Ans.
$\begin{aligned} & 4 \times 538 \times 25=538 \times 4 \times 25 \\ & =538 \times 100=53800 \end{aligned}$
Question 13
(a) 493580
(b) 1233950
(c) 2467900
(d) none of these
Ans. $24679 \times 92+24679 \times 8$
$\begin{aligned} & =24679 \times(92+8) \\ & =24679 \times 100=2467900 \end{aligned}$
Question 14
(a) 1625000
(b) 162500
(c) 325000
(d) 812500
Ans.
$\begin{aligned} & 1625 \times 1625-1625 \times 625 \\ & =1625(1625-625)=1625 \times 1000 \\ & =1625000 \end{aligned}$
Question 15
Q.15. $1568 \times 185-1568 \times 85=$ ?
(a) 7840
(b) 15680
(c) 156800
(d) none of these
Ans.
$\begin{aligned} & 1568 \times 185-1568 \times 85 \\ & =1568(185-85)=1568 \times 100 \\ & =156800 \end{aligned}$
Question 16
(a) 120
(b) 280
(c) 20
(d) 140
Ans. $888+777+555=111 \times$ ?
$=11(8+7+5)=111 \times 20$
Question 17
(a) an odd number
(b) an even number
(c) a prime number
(d) a multiple of 3
Ans.
The sum of two odd number is an even number
Question 18
(a) an odd number
(b) an even number
(c) a prime number
(d) none of these
Ans. The product of two odd numbers is an odd number
Question 19
(a) 1
(b) 2
(c) 3
(d) none of these
Ans. If a is a whole number such that
$\begin{aligned} & a+a=a \text {, then } a=0 \\ & \text { as } 0+0=0 \end{aligned}$
$\therefore$ None of these
Question 20
Q.20. the predecessor of 10000 is
(a) 10001
(b) 9999
(c) none of these
Ans. The predecessor of 10000 is
$10000-1=9999$
Question 21
(a) 1000
(b) 1002
(c) none of these
Ans. The successor of 1001 is $1001+11002$
Question 22
Q.22. The smallest even whole number is
(a) 0
(b) 2
(c) none of these
Ans. The smallest even whole number is 2
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