Which of the following numbers is divisible by 25?

Directions: Find the wrong number in the following number series:

0.5, 2, 1, 4, 32, 512, 16384

Find the greatest number 23a68b, which is divisible by 3 but NOT divisible by 9.

Find the sum of 2x terms of the series ( 1² - 2² + 3² - 4² + ___ ) 

If a certain number of two digits is divided by the sum of its digits, the quotient is 6 and the remainder is 3. If the digits are reversed and the resulting number is divided by the sum of the digits, the quotient is 4 and the remainder is 9. The sum of the digits of the number is 

The average of six consecutive odd numbers is 26. Find the difference between the largest and the smallest of these numbers.

The sum of the two - digit number is 6 and the number and its flip (digits written in reverse order) both are multiples of 3. If the difference between them is 36, then which of the following is the required number and its flip? 

3¹¹ + 3¹² + 3¹³ + 3¹⁴ is divisible by which of the following?