Answer: Option A. -> A
:
A
Only house number A begins with 5 in the thousands place.All other house numbers begin with 2 in the thousands place.
Hence A (5247) cannot be Rohan’s house number.

Answer: Option B. -> 80000 + 4000 + 900 + 20 + 6
:
B
84926 = 8 ten thousands +
4 thousands + 9 hundreds +
2 tens + 6 ones
= 80000 + 4000 + 900 + 20 + 6

Answer: Option B. -> 20990
:
B
To round off a number to the nearest ten, we checkthe last digitof the number.
If the lastdigitisless than 5, we round down the number to the nearest lower multiple of 10.
If the lastdigitis5or morethan 5, we round upthe number to the nearest highermultiple of 10.
In 20987, the digit in the ones place is 7. The nearest multiples of 10 for 20987 are 20980 or 20990.
Since7 is greater than5, 20987will be rounded off to 20990.

Answer: Option C. -> P is the smallest of all the numbers
:
C
We note that all 4 numbers have the same number of digits.
To findthe smallestnumberfrom the given numbers, we need to check the digit in the tens place for each number since the digits in the thousands and hundreds place are the same for all of them.
$\begin{array}{cc}\text{Number}& \text{Number of tens}\\ 28\underset{–}{0}9& 0\\ 28\underset{–}{9}9& 9\\ 28\underset{–}{5}0& 5\\ 28\underset{–}{9}0& 9\end{array}$
Since 9 > 5 > 0, the smallest number is P = 2809.
To find the largest number (which is either 2899 or 2890), we need to check the digit in the ones place.
Since 9> 0,the largest number is Q = 2899.

Answer: Option C. -> 1999
:
C
The largest 3-digit number is999.
The smallest 4-digit number is 1000.
Hence, their sum equals999 +1000 = 1999.

Answer: Option A. -> 52 is written as LII in Roman numerals.
:
A
52 =50 + 1 + 1 = L+ I + I = LII
102 = 100 + 1 + 1 = C + I + I = CII
140 = 100 + 40 = 100 + 50 - 10 = C + XL = CXL
42 = 40 + 1 + 1 = 50 - 10 + 1 + 1 = XL + I + I = XLII
Thus, the option "52 is written as LII in Roman numerals" is the only correct answer.

Answer: Option A. -> True
:
A
While writing a Roman Numeral, only the numerals I, X, C and M can be repeated. The numerals V, L and D cannot be repeated.

Answer: Option D. -> Rahul
:
D
To identifythe smallest number from a given set of numbers having equal number of digits, we need to compare the digitin the thousands place of each number.
$\begin{array}{cc}\text{Number}& \text{Number of thousands}\\ \underset{–}{6}572& 6\\ \underset{–}{7}297& 7\\ \underset{–}{5}425& 5\\ \underset{–}{1}252& 1\end{array}$
Since 7 > 6 > 5 > 1, thesmallest number is the one with 1 in the thousands place which is1252, written by Rahul.

Answer: Option D. -> Rahul
:
D

To identify the smallest number from a given set of numbers having equal number of digits, we need to compare the digit in the thousands place of each number.
$\begin{array}{cc}\text{Number}& \text{Number of thousands}\\ \underset{–}{6}572& 6\\ \underset{–}{7}297& 7\\ \underset{–}{5}425& 5\\ \underset{–}{1}252& 1\end{array}$
Since 7 > 6 > 5 > 1, the smallest number is the one with 1 in the thousands place which is 1252, written by Rahul.

Answer: Option A. -> True
:
A

While writing a Roman Numeral, only the numerals I, X, C and M can be repeated. The numerals V, L and D cannot be repeated.