99. The sum of first 45 natural numbers is :
100. The sum of all even natural numbers between 1 and 31 is
101. (51 + 52 + 53 + ... + 100) = ?
102. How many natural numbers are there between 23 and 100 which are exactly divisible by 6 ?
103. The sum of all two digit numbers divisible by 5 is
104. The sum of how many terms of the series 6 + 12 + 18 + 24 + ??. is 1800 ?
105. How many terms are there in the G.P. 3, 6, 12, 24,...., 384 ?
