Rationale: Whenever you are asked to find the number of digits, try to bring the number in multiples of 10. This way, we can wasily calculate the umber of 0's through the powers of 10
50^8 × 8^3 × 11 = (5^2*2)^8*2^9*11 = 5^16*2^17*11 = 2*11*10^16 = 22*10^16
Hence we would have 16 trailing 0's and the three digits from 22
Total digits = 2 + 16 = 18
The answer: (A)
Question: How many digits are in the number 50^8 × 8^3 × 11?
Options:
(A) 18
(B) 20
(C) 19
(D) 22
(E) 17
Reasoning: K + 2K +2 + 3K - 5 + 5K +1 = 11K -2
(11K -2)/4 = 63
11K = 63 * 4 +2 = 252 +2 = 254
K = 254 / 11 = 23 1/11
Ans: (E)
Question: If the average (arithmetic mean) of the four numbers K, 2K + 2, 3K – 5 and 5K + 1 is 63, what is the value of K?
Options:
(A)  11
(B)  15 3/4
(C)  22
(D)  23
(E)  23 1/11
Rationale: (60/100) * 50 – (40/100) * 30
30 - 12 = 18
The answer: (A)
Question: How much 60% of 50 is greater than 40% of 30?
Options:
(A) 18
(B) 99
(C) 66
(D) 55
(E) 71
Reasoning: 46080 /12 = 3840
3840 /10 = 384
384 /8 = 48
Ans: (A)
Question: What will come in place of the x in the following Number series? 46080, 3840, 384, x
Options:
(A) 48
(B) 3
(C) 4
(D) 5
(E) 6
Rationale: T = 60/36 * 18/5 = 6 sec
The answer: (D)
Question: In what time will a railway train 60 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 5 sec
(B) 4 sec
(C) 3 sec
(D) 6 sec
(E) 1 sec
Rationale: Sum of 10 even numbers = 10 * 11 = 110
Average = 110/10 = 11
The answer: (D)

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Question: The average of first 10 even numbers is?
Options:
(A) 17
(B) 199
(C) 16
(D) 11
(E) 123