# More Math Words

Here are some useful built-in words for common mathematical functions. You may skip this section, but use it as a reference later.
WordAction
`FLOOR`

Displays the floor of a number, which is the closest integer lower than the given number.

`CEIL`

Displays the ceiling of a number, which is the closest integer higher than the given number.

`ROUND`

Rounds off a real.

`MIN`

Minimum of a two numbers.

`MAX`

Maximum of a two numbers.

`^`

Exponentiation

`2 3 ^ `
becomes
`8`

`TANSINCOS`

Usual trigonometric functions.

`ATAN2`

The special arctangent, very useful for computing directions from vectors. A definition may be found here: Wikipedia: Atan2

`#e#pi`

Constant values of e and π.

`EXPLN`

Natural exponentiation and natural logarithms.

`LOG10`

Logarithms base 10.

`TO-DEGTO-RADIANS`

Converts angles to degrees or radians.

`MODFMOD`

Integer modulus and real modulus. Use FMOD if either operand is a real number.

`ABS`

The absolute value.

## Logical Operators

WordAction
`TRUE`

Puts the logical value

`true`
on the stack.

`FALSE`

Puts the logical value

`false`
on the stack.

`OR`

Logical or. For example,

`true 1 2 = OR`
becomes
`true`
.

`AND`

Logical and. For example,

`true 1 2 = AND`
becomes
`false`
.

## Quiz

### Question 1

Use words you learnt to find the truncation part of a number. For example,
`5.25 your code here .`
should display
`5.0`
.

### Question 2

There is a built-in word
`DUP`
that duplicates the top of the stack. For example,
`5.25 DUP`
ends up with
`5.25 5.25`
on the stack.
Use
`DUP`
and words you learnt to find the fractional part of a number. For example,
`5.25 your code here .`
should display
`0.25`
.

### Question 3

Do your solutions work for negative numbers?