Answer: Option A. -> CXCVIII
:
A
198 can be written as :
198 = 100+90+8
100 = C
90 = 100-10
90= XC
8 = VIII
$\therefore$ 198 = CXCVIII

Answer: Option B. -> 164
:
B
The sum of smallest 2 two-digit numbers = 10 + 10 = 20
And the sum of largest 2 digit numbers = 99 + 99 = 198
So, the sum of all the two-digit numbers will be between 20 and 198.
164 lies in between 20 and 198. So the sum that can be obtained is only 164.
18,199,285 do not lie between20 and 198, so they can not be the sum of 2 two-digit numbers.

Answer: Option C. -> MMCDXCIX
:
C
2499 = 2000 + 400 + 90 + 9
= MM + CD + XC + IX
= MMCDXCIX
($\because$ 2000 = MM, 400 = CD, 90 = XC, 9 = IX)

Answer: Option B. -> 3600
:
B
Place values of 6 in438269160 are $6\times 10000=60000$ and $6\times 10=60$.
The product of the place values of 6 in 438269160 divided by 1000$=\frac{60000\times 60}{1000}=\frac{3600000}{1000}=3600$

Answer: Option C. -> 58000
:
C

To round off a number to its nearest thousand we checkthe last three digits of the number i.e. the digits at the hundredsplace, tens place and ones place. In case the number formed by these is 500 or above, we round up the number to the higher value and in case the number is less than 500, we round it down to the lower value.
The given number is 58195. Our options are 58000 and 59000. The last three digits of 58195 are 195.
195 < 500.
Therefore58195 when rounding off to the nearest thousandis 58000.

Answer: Option D. -> 9
:
D
The given options of odd numbers are: 3, 5, 7, 9.
Here3, 5 and 7 are prime numbers.
So, 9 is the smallest odd composite number.

Answer: Option B. -> 101100
:
B
The successor of a number is the number that comes right after it.
Thus, thesuccessor of 101099 is
101099 + 1 = 101100.

Answer: Option A. -> 7
:
A
$\begin{array}{ccccccc}I& V& X& L& C& D& M\\ 1& 5& 10& 50& 100& 500& 1000\end{array}$
There are the 7 basic symbols in Roman numerals.

Answer: Option C. -> 2
:
C
1 million = 1,000,000
The successor of a number is one morethan that number and the predecessor of a number is one less than that number.
The successor of 1,000,000 = 1000000+ 1 = 1000001
The predecessor of 1,000,000 = 1000000- 1 = 999999
The difference between the successor and the predecessor of1,000,000 = 1000001 - 999999= 2.
In fact the difference between the successor and predecessor of any number will always be 2 !! Try it yourself

Answer: Option D. -> 1000000
:
D
1 crore $=1,00,00,000$
Number of tens in 1 crore
$=\frac{10000000}{10}=1000000$
$\therefore 1000000$ tens make 1 crore.