If we write down all the natural numbers from 259 to 492 side by side get a very large natural number 259260261....491492. How many 8's will be used to write this large natural number?
Answer: D From 259 to 458, there are 200 natural numbers so there will be 2*20 =40 8's From 459 to 492 we have 13 more 8's and so answer is 40+13 =53
Q. No. 14:
When 75% of a two-digit number is added to it, the digits of the number are reversed. Find the ratio of the unit's digit to the ten's digit in the original number.
Answer: B Any power of 5 when divided by 4 gives a remainder 1. Here the power of 3 is itself a power of 5 and will give remainder of 1 when divided by 4. The last digit of the number will be 3. And, hence, last digit of the given number is 3+1 =4.
Q. No. 16:
A wrote all the numbers from 100 to 200. Then she started counting the number of one's that has been used while writing all these numbers. What is the number that she got?
Answer: C From 100 to 200 there are 101 numbers. There are 100 1's in the hundred place. 10 1's in tens place 10 1's in unit place Thus the answer is 100+10+10 = 120.
Q. No. 17:
What is the remainder when 7187 is divided by 800?
Answer: C 7187 = (74)46 * 73 = (2401)46*343 Now 2410 = 2400+1 (2401)46 is divided by 800, the remainder must be 1.So, the remainder when 7187 is divided by 800 is 1*343 = 343
Q. No. 18:
When a particular positive number is divided by 5, the remainder is 2. If the same number is divided by 6, the remainder is 1. If the difference between the quotients of division is 3, then find the number.
Answer: B Let the quotients when this number is divided by 5 and 6 be x and y respectively. (Note that x will be greater than y as 5 is smaller than 6). Number = 5x+2 = 6y+1 Given that, x-y =3 On solving both equation we get, x= 19, y= 16 Thus the number is 19*5 + 2 = 97.