Math Expressions: unfamiliar operators

Question 1

Code a short form of x = x + 1; Use either of the two legal expressions.

Answer 1

x++; or ++x;

Question 2

If x has a value of 100, what is the fastest way to reduce it to 99 with a math expression? Use either of the two legal expressions.

Answer 2

x–; or –x;

Question 3

var x = 50;
var y = x++;
What is the value of y?

Answer 3

50

Question 4

var x = 50;
var y = --x;

Answer 4

49

Question 5

In a single statement, increment the variable num and assign its new value to a second variable, newNum, which hasn’t been declared beforehand.

Answer 5

var newNum = ++num;

Question 6

In a single statement, decrement num and assign its original value to newNum, which hasn’t been declared beforehand.

Answer 6

var newNum = num–;

Question 7

Using minimal code, decrement x. Use either of the two legal expressions.

Answer 7

x–; or –x;

Question 8

What is the long version of x++?

Answer 8

x = x + 1;

Question 9

In a single statement subtract 1 from a variable and assign the new value to another variable, which hasn’t been declared beforehand. Both variables wind up with the same value.

Answer 9

var newNum = –num;

Question 10

In a single statement add 1 to a variable and assign its original value to another variable, which hasn’t been declared beforehand.

Answer 10

var newNum = num++;

Question 11

Increment a variable. Use either of the two legal expressions. In a second statement, display its new value in an alert.

Answer 11

num++; or ++num;

alert(num);