If a + b=ab and a, b are natural numbers then how many pairs of (a, b) are there? Answer: 1 pair – (2, 2) Explanation a + b = ab ab – a – b = 0 ab – a – b + 1 = 1 (a – 1)(b – 1) = 1 Now, for this to be true, given that a and b are natural numbers a – 1 = b – 1 = 1. i.e., 1 x 1 = 1 Therefore, a = 2 and b = 2. … [Read more...] about Numerical entry – Number Properties

# GRE Numerical Entry

## Numeric Entry – Probability, Number Properties

A four-digit number is to be formed with the digits {0, 1, 2, 3, 4, 5} without repetition. What is the probability that this number will leave a remainder 2 when divided by 9? Answer: 0.14 Explanation Required probability = (number of four digit numbers that leave a remainder 2 when divided by 9) / (total number of four digit numbers that can be formed) If a … [Read more...] about Numeric Entry – Probability, Number Properties

## Numerical Entry – Permutations and Combinations

A manager is forming a 6-person team to work on a certain project. From the 11 candidates available for the team, the manager has already chosen 3 to be on the team. In selecting the other 3 team members, how many different combinations of 3 of the remaining candidates does the manager have to choose from? Answer: 56 Explanation The manager has to form a 6-person … [Read more...] about Numerical Entry – Permutations and Combinations