Numbers Questions Answers

1. Simplify 586645 * 9999
 5865863355
 5665863355
 4865863355
 4665863355
Answer And Explanation
Answer: Option A
Explanation:
Although it is a simple question, but the trick is to save time in solving this.
Rather than multiplying it we can do as follows:
586645 * (10000  1) = 5866450000  586645 = 5865863355 
2. 1939392 * 625
 1212120010
 1212120000
 1212120011
 1212121010
Answer And Explanation
Answer: Option B
Explanation:
Trick: when multiplying with \begin{aligned} 5^n
\end{aligned} then put n zeros to the right of multiplicand and divide the number with \begin{aligned} 2^n
\end{aligned}
So using this we can solve this question in much less
time.
\begin{aligned} 1939392 \times 5^4 = \frac {19393920000}{16} = 1212120000
\end{aligned} 
3. Simplify (212 * 212 + 312 * 312 )
 132288
 142088
 142188
 142288
Answer And Explanation
Answer: Option D
Explanation:
Trick: Above equation can be solved by using following formula
\begin{aligned}
(a^2 + b^2) = \frac{1}{2}((a+b)^2 + (ab)^2)
\end{aligned} 
4. Find the unit digit in \begin{aligned}
(544)^{102} + (544)^{103}
\end{aligned} 2
 4
 0
 1
Answer And Explanation
Answer: Option C
Explanation:
Required digit is = \begin{aligned}
(4)^{102} + (4)^{103} \end{aligned}
as \begin{aligned} (4)^2 \end{aligned} gives unit digit 6 so \begin{aligned} (4)^{102} \end{aligned} unit digit is 6 and \begin{aligned} (4)^{103} \end{aligned} unit digit is, unit digit of \begin{aligned} 6 \times 4 \end{aligned}= 4, so answer will be unit digit of 6 + 4 = 0

5. What least value should be replaced by * in 223*431 so the number become divisible by 9
 3
 4
 5
 6
Answer And Explanation
Answer: Option A
Explanation:
Trick: Number is divisible by 9, if sum of all digits is divisible by 9, so (2+2+3+*+4+3+1) = 15+* should be divisible by 9,
15+3 will be divisible by 9,
so that least number is 3. 
6. How many terms are there in 2,4,8,16,....,1024
 7
 8
 9
 10
Answer And Explanation
Answer: Option D
Explanation:
It is a GP. with r = 2, ie \begin{aligned} 2^1, 2^2, 2^3... \end{aligned}
If number of terms is n. Then,
\begin{aligned} 2 \times 2^{n1} = 1024 \end{aligned} =>
\begin{aligned} 2^{n1} = 512 \end{aligned}
or \begin{aligned} 2 \times 2^{n1} = 2^9 \end{aligned}
so n1 = 9 => n = 10 
7. Which of the following is a prime number
 9
 2
 4
 8
Answer And Explanation
Answer: Option B
Explanation:
A prime number is a natural number greater than 1 which has no positive divisors other than 1 or itself.
So from above options 2 is that number

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but plz include more question which matches difficulty level of the question that come in exam. 
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Rajesh Bagodi 4 years ago
It really helps!!

Vijay Kiran R 4 years ago
Error in question 6
2×2^n?1=2^9 is wrong...
It must be
2×2^n?1=2^10 
sunny 5 years ago
LOD is not that gud :(

eswarapandian 5 years ago
nice.