Answer: C A number is divisible by 8 , if the number formed by the last three digits is divisible by 8. i.e 58N is divisible by 8 => N=4 Again a number is divisible by 11, if the difference between the sum of digits at even places and sum of digits at the odd places is either 0 or divisible by 11. i.e, (M+9+4+4+8) - (3+0+8+5+N) = M-N+9 = M+5 It cannot be zero hence, M+5 =11 => M=6.
Q. No. 8:
The LCM of two numbers is 280 and their ratio is 7:8. The two numbers are
Answer: A Sum of digits from 1 to 10 = 46 sum of digits from 11 to 20 =56 sum of digits from 21 to 29 =63 sum of the digits from numbers = 46+56+63 =165 Sum of digits in the number 165 =12 which gives a remainder of 3 when divided by 9.
Q. No. 10:
If N=23*34 , M= 22*35, then find the number of factors of N that are common with the factors of M.
Answer: B The factors that are common must also be the factors of HCF(N,M) HCF(N,M) = 22*34 Number of factors of 22*34 = (2+1)(4+1) = 15 so there are 15 factors that are common to both.
Q. No. 11:
A and B are playing mathematical puzzles. A asks B "which whole numbers, greater than one, can divide all the nine three digit numbers 111, 222, 333, 444, 555, 666, 777, 888 and 999?" B immediately gave the desired answer. It was