For the integer n, if n*n*n is odd, then what is true
n is odd and n*n is even
n*n is odd
n is even
n*n is odd
Answer: Option A
Similar Questions :
1. Which of the following is a prime number
9
2
4
8
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
2. How many terms are there in 2,4,8,16,....,1024
7
8
9
10
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^{n-1} = 1024 \end{aligned} =>
\begin{aligned} 2^{n-1} = 512 \end{aligned}
or \begin{aligned} 2 \times 2^{n-1} = 2^9 \end{aligned}
so n-1 = 9 => n = 10
3. What least value should be replaced by * in 223*431 so the number become divisible by 9
3
4
5
6
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.
4. 1939392 * 625
1212120010
1212120000
1212120011
1212121010
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}