diff --git a/src/evaluator.rs b/src/evaluator.rs
index b33ce96..b216e10 100644
--- a/src/evaluator.rs
+++ b/src/evaluator.rs
@@ -83,10 +83,32 @@ fn evaluate_node(ast_node: &AstNode) -> Result<Answer, String> {
             return Err(format!("exp() only accepts UnitType::NoUnit").to_string())
           }
         },
-        // Ceil
-        // Floor
-        // Round
-        // Fabs,
+        Round => {
+          // .quantize() rounds .5 to nearest even integer, so we correct that
+          let mut result = child_answer.value.quantize(d128!(1));
+          let rounding_change = result - child_answer.value;
+          // If the result was rounded down by 0.5, correct by +1
+          if rounding_change == d128!(-0.5) { result += d128!(1); }
+          return Ok(Answer::new(result, child_answer.unit))
+        },
+        Ceil => {
+          let mut result = child_answer.value.quantize(d128!(1));
+          let rounding_change = result - child_answer.value;
+          if rounding_change.is_negative() { result += d128!(1); }
+          return Ok(Answer::new(result, child_answer.unit))
+        },
+        Floor => {
+          let mut result = child_answer.value.quantize(d128!(1));
+          let rounding_change = result - child_answer.value;
+          if !rounding_change.is_negative() { result -= d128!(1); }
+          return Ok(Answer::new(result, child_answer.unit))
+        },
+        Abs => {
+          let mut result = child_answer.value.abs();
+          let rounding_change = result - child_answer.value;
+          if rounding_change == d128!(-0.5) { result += d128!(1); }
+          return Ok(Answer::new(result, child_answer.unit))
+        },
 
         // Sin,
         // Cos,
diff --git a/src/lexer.rs b/src/lexer.rs
index cf0440d..8fece60 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -5,7 +5,7 @@ use crate::Operator::{Caret, Divide, LeftParen, Minus, Modulo, Multiply, Plus, R
 use crate::UnaryOperator::{Percent, Factorial};
 use crate::TextOperator::{Of, To};
 use crate::Constant::{E, Pi};
-use crate::FunctionIdentifier::{Acos, Acosh, Asin, Asinh, Atan, Atanh, Cbrt, Ceil, Cos, Cosh, Exp, Fabs, Floor, Ln, Log, Round, Sin, Sinh, Sqrt, Tan, Tanh};
+use crate::FunctionIdentifier::{Acos, Acosh, Asin, Asinh, Atan, Atanh, Cbrt, Ceil, Cos, Cosh, Exp, Abs, Floor, Ln, Log, Round, Sin, Sinh, Sqrt, Tan, Tanh};
 use crate::units::Unit::*;
 
 pub fn lex(input: &str) -> Result<TokenVector, String> {
@@ -76,10 +76,10 @@ pub fn lex(input: &str) -> Result<TokenVector, String> {
           "ln" => tokens.push(Token::FunctionIdentifier(Ln)),
           "exp" => tokens.push(Token::FunctionIdentifier(Exp)),
 
+          "round" | "rint" => tokens.push(Token::FunctionIdentifier(Round)),
           "ceil" => tokens.push(Token::FunctionIdentifier(Ceil)),
           "floor" => tokens.push(Token::FunctionIdentifier(Floor)),
-          "round" | "rint" => tokens.push(Token::FunctionIdentifier(Round)),
-          "fabs" => tokens.push(Token::FunctionIdentifier(Fabs)),
+          "abs" | "fabs" => tokens.push(Token::FunctionIdentifier(Abs)),
 
           "sin" => tokens.push(Token::FunctionIdentifier(Sin)),
           "cos" => tokens.push(Token::FunctionIdentifier(Cos)),
diff --git a/src/main.rs b/src/main.rs
index 9b56295..4076d76 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -42,10 +42,10 @@ pub enum FunctionIdentifier {
   Ln,
   Exp,
   
+  Round,
   Ceil,
   Floor,
-  Round,
-  Fabs,
+  Abs,
 
   Sin,
   Cos,