Number System

61 A student was asked to divide a number by 6 and add 12 to the result. But, instead of deviving he first added 12 to the number and the divided it by 6, get 112 as the answer. The correct answer could be:

62 The smallest number in five consecutive even numbers is one more than the largest number in six consecutive odd numbers. Find out the difference between the square of the second largest even number and the square of the second smallest odd number, if the sum of the smallest odd number and second smallest even number is 75?

63 1/10 of a rod is coloured white, 1/20 orange, 1/30 yellow, 1/40 green, 1/50 blue, 1/60 black and the rest is indigo. If the length of the indigo portion of the rod is 12.08 m, find the length of the rod is:

64 What is the value of: 2² +4² +6² +........... +20²

65 Sanjay has a wrong weighing pan. One kilogram on left balances 8 oranges on right, 1 kilogram on right balances 2 oranges on left. If all oranges are equal in weight, what is the weight of a single orange:

66 OWhen dividing a number by 68, we get 269 as quotient and zero as remainder. On dividing the same number by 67, what will be the remainder ?

67 The difference of the squares of two consecutive odd number is always divisible by which of the following integers ?

68 When multiplying a number by 7, the product number comes in a way that each of the digit's is 3. The smallest such number is:

69 If a and b are odd numbers, then which of the following is even ?

70 $${\frac{1}{2} + \frac{1}{6} + \frac{1}{12} + \frac{1}{20} + ............ + \frac{1}{n(n+1)}}$$ ?