Question 511 Mark
Every multiple of a number is greater than or equal to the number.
Question 521 Mark
The $LCM$ of two coprime numbers is equal to product of the numbers.
Answer Consider a pair of coprime numbers $3$ and $4.$
$HCF$ of $3$ and $4 = 1$
$LCM \times HCF =$ Product of the two numbers Now,
$LCM \times HCF = 3 \times 4 $
$\Rightarrow LCM \times 1 = 3 \times 4 $
$\Rightarrow LCM = 12$
View full question & answer→Question 531 Mark
Natural numbers are closed under subtraction.
AnswerSince, the difference of any two natural numbers is not always a natural number.
View full question & answer→Question 541 Mark
Successor of a one-digit number is always a one-digit number.
AnswerSince, successor of a one-digit number may be a two-digit number. e.g.
Let one-digit number be $9.$
Then, successor of $9 = 9 + 1 = 10,$
which is a two-digit number.
View full question & answer→Question 551 Mark
Every whole number is the successor of another whole number.
AnswerSince, $0$ (whole number) is not the successor of any whole number.
View full question & answer→Question 561 Mark
$2395\ \times $ _________ $= 6195 \times 2395.$
Answer$2395 \times 6195 = 6195 \times 2395.$
Solution: If $a$ and $b$ are two whole numbers,
then $a \times b = b \times a [$by commutative property$]$
View full question & answer→Question 571 Mark
If the $HCF$ of two numbers is one of the numbers, then their $LCM$ is the other number.
AnswerSince, $HCF \times LCM =$ First number $\times$ Second number
View full question & answer→Question 581 Mark
The number of factors of a prime number is ___________.
AnswerEvery prime number has only two factors, $1$ and the number itself.
View full question & answer→Question 591 Mark
$a.\ 10$ million $= .......$ crore $10.$
$b.\ $ lakh $= ........$ million.
Answer$a.$ We know that,
$1$ crore $= 100$ lakh and $1$ million $= 10$ lakh
$1$ crore $= 10$ million
$b.$ We know that,
$1$ million $= 10$ lakh
View full question & answer→Question 601 Mark
Successor of a $3-$digit number is always a $3-$digit number.
AnswerSince, successor of a $3-$digit number cannot be always a $3-$digit number, e.g. Successor of $999 = 999 + 1 = 1000$
View full question & answer→Question 611 Mark
$1$ is the identity for multiplication of whole numbers.
AnswerIf a is any whole number, then $a \times 1 = a$
View full question & answer→Question 621 Mark
$LXXIV = 74$
AnswerSince, $LXXIV = 50 + 10 + 10 + 4 = 74$
View full question & answer→Question 631 Mark
Any two consecutive numbers are coprime.
AnswerBy definition, coprime numbers are those numbers, whose $HCF$ is $1.$
View full question & answer→Question 641 Mark
$1$ is identity for addition of whole numbers.
AnswerSince, $1$ is the identity for multiplication of whole numbers.
View full question & answer→Question 651 Mark
$1001 \times 2002 = 1001 \times (1001 +$ ________$).$
Answer$1001 \times 2002 = 1001 \times (1001 + 1001).$
Solution:
Let $x$ be the missing number, then $1001 \times 2002 = 1001(1001 + x) $
$\Rightarrow 2002 = (1001 + x) $
$\Rightarrow 2002 - 1001 = x$
$\therefore x = 1001$
View full question & answer→Question 661 Mark
A number is divisible by __________ if it has any of the digits $0, 2, 4, 6$ or $8,$ in its ones place.
AnswerAccording to the divisibility test for $2,$
if the last digit of a number is either $0$ or $2$ or $4$ or $6$ or $8,$
then the number is divisible by $2.$
View full question & answer→Question 671 Mark
By reversing the order of digits of the greatest number made by five different non-zero digits, the new number is the __________ number of five digits.
Answer For making smallest number from given digits, we arrange them in ascending order and for greatest number, we arrange them in descending order.
View full question & answer→Question 681 Mark
A whole number divided by another whole number greater than $1,$ never gives the quotient equal to the former.
View full question & answer→Question 691 Mark
Natural numbers are closed under __________ and under ____________.
AnswerNatural numbers are closed under addition and under multipication.
Solution:
If $a$ and $b$ are any two natural numbers,
then $a + b = c ($natural numbers$)$
Also, $a \times b = c ($natural numbers$)$
View full question & answer→Question 701 Mark
If the sum of the digits of a number is divisible by $3,$ then the number itself is divisible by $9.$
AnswerAccording to the divisibility test of $9,$ a number is divisible by $9,$ if the sum of the digits of a number is divisible by $9.$
View full question & answer→Question 711 Mark
The smallest whole number is _______.
AnswerWe know that, whole numbers start from $0.$
Therefore, the smallest whole number is $0.$
View full question & answer→Question 721 Mark
The highest common factor of two or more numbers is greater than their lowest common multiple.
Answer Since, $HCF$ of two or more numbers is less than their lowest common multiple.
View full question & answer→Question 731 Mark
Predecessor of $100000$ is __________.
AnswerFor getting predecessor of the given number,
we subtract $1$ from the given number.
So, predecessor of $100000 = 100000 - 1 = 99999$
View full question & answer→Question 741 Mark
$125 + (68 + 17) = (125 + $______ $) + 17$
Answer$125 + (68 + 17) = (125 + 68) + 17$
Solution: If $a, b$ andc are three whole numbers,
then $a + (b + c) = (a + b) + c [$by associative property$]$
View full question & answer→Question 751 Mark
Sum of two distinct whole numbers is always less than their product.
AnswerLet us understand this through example.
$1 + 2 = 3$ and $1 \times 2 = 2$
Here, sum $(3)\ > $ product $(2)$ We can say that sum of two whole numbers is not always less than their product.
View full question & answer→Question 761 Mark
A number is divisible by $5,$ if it has _________ in its ones place.
AnswerAccording to divisibility test for $5,$
if a number has $0$ or $5$ in its ones place,
then it is divisible by $5.$
View full question & answer→Question 771 Mark
$a.\ 1$ gram $= ......$ milligrams.
$b.\ 1$ litre $= ......$ millilitres.
$c.\ 1$ kilogram $= .......$ milligrams.
Answer$a.\ 1\ g = 1000\ mg$
$b.\ 1\ L = 1000\ mL$
$c.$ We know that,
$1000\ mg = 1\ g$ and $1000\ g = 1\ kg$
$1\ kg = (1000 \times 1000)\ mg$
$= 1000000\ mg$ View full question & answer→Question 781 Mark
The number $LIV$ is greater than $LVI.$
AnswerSince, $LIV = 50 + 4 = 54$
$LVI = 50 + 5 + 1 = 56$
$\therefore LVI > LIV$
View full question & answer→Question 791 Mark
Two numbers having only $1$ as a common factors, are called __________ numbers.
AnswerTwo numbers having only $1$ as a common factors, are called coprime numbers.
View full question & answer→Question 801 Mark
In Roman numeration, the symbol $X$ can be subtracted from __________ $M$ and $C$ only.
AnswerBy general rule, in Roman numeration, the symbol $X$ can be subtracted from $L, M$ and $C$ only.
View full question & answer→Question 811 Mark
$2$ is the only ________ number, which is even.
Answer$2$ is the only prime number, which is even.
Solution:
Those numbers which are divisible by $1$ and the number itself, are known as prime numbers.
$2$ is the only prime number which is even.
View full question & answer→Question 821 Mark
Every whole number has its successor.
Question 831 Mark
All numbers which are divisible by $4,$ may not be divisible by $8.$
AnswerSince, $4$ is divisible by $4,$ but it is not divisible by $8.$
View full question & answer→Question 841 Mark
$24 \times 35 = 24 \times 18 + 24\ \times $_______
AnswerLet a be the missing number, then
$24 \times 35 = 24 \times 18 + 24 \times a $
$\Rightarrow 24 \times 35 - 24 \times 18 = 24 \times a $
$\Rightarrow 24(35 - 18) = 24 \times a $
$\Rightarrow 24 \times 17 = 24 \times a$
$\therefore a = 17$
View full question & answer→Question 851 Mark
Natural numbers are not closed under multiplication.
AnswerSince, the sum of any two natural numbers is always a natural number.
View full question & answer→Question 861 Mark
$XXIX = 31$
AnswerSince, $XXIX = 10 + 10 + 9 = 29 \neq 31$
View full question & answer→Question 871 Mark
$82546 = 8 \times 1000 + 2 \times 1000 + 5 \times 100 + 4 \times 10 + 6$
AnswerSince, $8 \times 1000 + 2 \times 1000 + 5 \times 100 + 4 \times 10 + 6 \times 1$
$= 8000 + 2000 + 500 + 40 + 6 = 10546 \neq 82546$
View full question & answer→Question 881 Mark
The $HCF$ of two or more given numbers is the highest of their common ____________.
AnswerThe $HCF$ of two or more given numbers is the highest of their common factors.
View full question & answer→Question 891 Mark
Multiplication is distributive over ___________ for whole numbers.
AnswerMultiplication is distributive over addition for whole numbers.
Solution:
If $a, b$ and $c$ are three whole numbers,
then $a(b + c) = (a \times b) + (a \times c)$
View full question & answer→Question 901 Mark
Every whole number has its predecessor.
AnswerSince, every whole number does not have a predecessor, e.g. $0$ does not have a predecessor.
View full question & answer→Question 911 Mark
$32 \times (27 \times 19) = (32 \times $ ______$) \times 19$
Answer$32 \times (27 \times 19) = (32 \times 27) \times 19$
Solution: If $a, b$ and $c$ are any three natural numbers,
then $a \times (b \times c) = (a \times b) \times c [$by multiplicative property$]$
View full question & answer→Question 921 Mark
The largest six-digit telephone number that can be formed by using digits $5, 3, 4, 7, 0$ and $8$ only once, is $875403.$
AnswerSince, for making largest six-digit number,
we arrange the given digits in descending order,
we get i.e. $8, 7, 5, 4, 3$ and $0.$
Largest six-digit number $= 875430$
View full question & answer→Question 931 Mark
The number $85764$ rounded off to nearest hundreds is written as $85700.$
AnswerSince, rounded off $85764$ to nearest hundreds $= 85800$
View full question & answer→Question 941 Mark
Successor of $106159$ is _________.
AnswerFor getting successor of the given number,
we add $1$ to the given number.
So, successor of $106159 = 106159 + 1 = 106160$
View full question & answer→Question 951 Mark
The numbers $4578, 4587, 5478$ and $5487$ are in descending order.
AnswerSince, in descending order, we arrange the given numbers from largest to smallest,
$5487 > 5478 > 4587 > 4578$
View full question & answer→Question 961 Mark
The numbers having more than two factors are called __________ numbers.
AnswerThe numbers having more than two factors are called composite numbers.
View full question & answer→Question 971 Mark
$10001 \times 0 = $_________.
AnswerIf any number is multiplied by zero, then their product is always zero.
View full question & answer→Question 981 Mark
The smallest $4-$digit number is the successor of the largest $3-$digit number.
AnswerSince, the largest $3-$digit number $= 999$
Successor of $999 = 999 + 1 = 1000 [$smallest $4-$digit number$]$
View full question & answer→Question 991 Mark
_________ is a factor of every number.
AnswerWe know that, $1$ is a factor of every number.
View full question & answer→Question 1001 Mark
Number of primes between $1$ to $100$ is __________.
AnswerPrime numbers between $1$ to $100$ are $2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89$ and $97.$
Number of prime numbers between $1$ to $100 = 25$
View full question & answer→