2.e Skills

Question 1

When you get asked a question with a weird number like 0.443, what should you do?

Answer 1

Use a strategic number like 1/2 !

Question 2

What if we get asked 113/11, how can we do this quickly?

Answer 2

Consider estimating!

100/10 = 10

The actual answer is 10.27, which is relatively close

Question 3

The GMAT may ask you to find the answer to a question like: 9007², how would you do this easily?

Answer 3

The last number of the answer MUST be 9.

This is because 9007², and we can do 7² = 49. The last number 49 = 9, so in the answer of 9007², 9 must be the units (last) digit.

If all multiple choice answers are unique, this alone should give you the answer.

Question 4

What is a perfect square?

Answer 4

5² = 25, 25 is a perfect square

Question 5

If n is a perfect square, which of the following could be n?

Answer 5

III only,

Perfect squares all end in 0, 1, 4, 5, 6 or 9.

Question 6

What is an opposite number?

Answer 6

The opposite of a number is the number with the opposite sign

Question 7

What is the opposite of 8?

Answer 7

Opposite of 8 is -8

Question 8

What is the opposite of -6?

Answer 8

Opposite of -6 is 6

Question 9

What is an absolute value?

Answer 9

An absolute value of a number is the number without the sign, and it is denoted by two bars.

Question 10

How are absolute values denoted?

Answer 10

By two bars on the sides.

Question 11

What is the absolute value of 9?

Answer 11

9

Question 12

What is the absolute value of -9?

Answer 12

9

Question 13

What acronym could you use to remember the order of mathematical operations?

Answer 13

PEMDAS

Question 14

What does PEMDAS stand for?

Answer 14

P = Parentheses
E = Exponents
M/D = Multiplication and Division
A/S = Addition and Subtraction

Question 15

What priority do absolute value bars have?

Answer 15

They are not included in PEMDAS, but they have the same priority as parentheses. So they take the highest priority just like parentheses do.

Question 16

What order would you complete this in?

Answer 16

In a fraction with addition and/or subtraction in the numerator and/or denominator. The operation must be completed prior to dividing the numerator by the denominator.

Question 17

What is the most efficient way to calculate: 44 x 87 + 56 x 87?

Answer 17

44 x 87 + 56 x 87

87 is a common factor across both products, so you can simply do
87 (44 + 56) = 87 x 100 = 8700

Question 18

What is the symbol for a factorial?

Answer 18

Exclamation mark

Question 19

What is a factorial?

Answer 19

If n is a positive integer, the factorial of n (n!) represents the product of all the integers from 1 to n.

Question 20

What is 5!

Answer 20

5 x 4 x 3 x 2 x 1 = 120

Question 21

What is 0!

Answer 21

1

Question 22

What is 1!

Answer 22

1

Question 23

What is the easiest way to solve: 11! + 12!

Answer 23

considering 12! = 11! x 12

we can just write:
11! + 11! x 12

11! ( 1 + 12 )
11! (13)