diff --git a/kalk/src/kalk_num.rs b/kalk/src/kalk_num.rs
index 320332d..5bddcc1 100644
--- a/kalk/src/kalk_num.rs
+++ b/kalk/src/kalk_num.rs
@@ -56,6 +56,10 @@ impl KalkNum {
         }
     }
 
+    pub fn to_string_big(&self) -> String {
+        self.value.to_string()
+    }
+
     pub fn is_too_big(&self) -> bool {
         self.value.is_infinite()
     }
diff --git a/kalk_cli/src/main.rs b/kalk_cli/src/main.rs
index 0721602..2b3dc6e 100644
--- a/kalk_cli/src/main.rs
+++ b/kalk_cli/src/main.rs
@@ -6,12 +6,15 @@ use std::env;
 use std::fs::File;
 use std::io::Read;
 
+static DEFAULT_PRECISION: u32 = 53;
+
 fn main() {
     let mut parser_context = parser::Context::new().set_angle_unit(&get_angle_unit());
 
     // Command line argument input, execute it and exit.
     let mut args = env::args().skip(1);
     let mut expr_input: Option<String> = None;
+    let mut precision = DEFAULT_PRECISION;
     loop {
         // Get the next argument if possible, otherwise break the loop.
         let arg = if let Some(arg) = args.next() {
@@ -28,8 +31,9 @@ fn main() {
 [kalk help]
 
 kalk [OPTIONS] [INPUT]
--h, --help : show this
--i         : load a file with predefined functions/variables
+-h, --help  : show this
+-i          : load a file with predefined functions/variables
+--precision : specify number precision
 
 [Environment variables]
 ANGLE_UNIT=(deg/rad) : Sets the default unit used for trigonometric functions.
@@ -47,9 +51,16 @@ ANGLE_UNIT=(deg/rad) : Sets the default unit used for trigonometric functions.
 
                 // Parse the input file content, resulting in the symbol table being filled out.
                 // Output is not needed here.
-                parser::eval(&mut parser_context, &file_content, 53)
+                parser::eval(&mut parser_context, &file_content, precision)
                     .expect("Failed to parse input file.");
             }
+            "--precision" => {
+                precision = args
+                    .next()
+                    .expect("Expected precision input.")
+                    .parse::<u32>()
+                    .expect("Precision value could not be parsed.");
+            }
             _ => {
                 // Main argument. This is expected to be a maths expression.
                 // After the loop is finished, this will be parsed and outputted.
@@ -60,10 +71,10 @@ ANGLE_UNIT=(deg/rad) : Sets the default unit used for trigonometric functions.
 
     if let Some(input) = expr_input {
         // Direct output
-        output::eval(&mut parser_context, &input);
+        output::eval(&mut parser_context, &input, precision);
     } else {
         // REPL
-        repl::start(&mut parser_context);
+        repl::start(&mut parser_context, precision);
     }
 }
 
diff --git a/kalk_cli/src/output.rs b/kalk_cli/src/output.rs
index 52dda88..6a01999 100644
--- a/kalk_cli/src/output.rs
+++ b/kalk_cli/src/output.rs
@@ -1,14 +1,17 @@
+use crate::DEFAULT_PRECISION;
 use ansi_term::Colour::Red;
 use kalk::parser::{self, CalcError, CalcError::*};
 
-pub fn eval(parser: &mut parser::Context, input: &str) {
-    match parser::eval(parser, input, 53) {
+pub fn eval(parser: &mut parser::Context, input: &str, precision: u32) {
+    match parser::eval(parser, input, precision) {
         Ok(Some(result)) => {
             let sci_notation = result.to_scientific_notation();
             let result_str = if sci_notation.exponent > 8 || sci_notation.exponent < -6 {
                 sci_notation.to_string()
-            } else {
+            } else if precision == DEFAULT_PRECISION {
                 result.to_string()
+            } else {
+                result.to_string_big()
             };
 
             println!("{} {}", result_str, result.get_unit());
diff --git a/kalk_cli/src/repl.rs b/kalk_cli/src/repl.rs
index 23fb94a..83b7240 100644
--- a/kalk_cli/src/repl.rs
+++ b/kalk_cli/src/repl.rs
@@ -18,7 +18,7 @@ use std::borrow::Cow::Owned;
 use std::collections::HashMap;
 use std::process;
 
-pub fn start(mut parser: &mut parser::Context) {
+pub fn start(mut parser: &mut parser::Context, precision: u32) {
     let mut editor = Editor::<RLHelper>::new();
     editor.set_helper(Some(RLHelper {
         highlighter: LineHighlighter {},
@@ -36,7 +36,7 @@ pub fn start(mut parser: &mut parser::Context) {
         match readline {
             Ok(input) => {
                 editor.add_history_entry(input.as_str());
-                eval_repl(&mut parser, &input);
+                eval_repl(&mut parser, &input, precision);
             }
             Err(ReadlineError::Interrupted) => break,
             _ => break,
@@ -44,12 +44,12 @@ pub fn start(mut parser: &mut parser::Context) {
     }
 }
 
-fn eval_repl(parser: &mut parser::Context, input: &str) {
+fn eval_repl(parser: &mut parser::Context, input: &str, precision: u32) {
     match input {
         "" => eprint!(""),
         "clear" => print!("\x1B[2J"),
         "exit" => process::exit(0),
-        _ => output::eval(parser, input),
+        _ => output::eval(parser, input, precision),
     }
 }