diff --git a/phino.cabal b/phino.cabal
--- a/phino.cabal
+++ b/phino.cabal
@@ -1,7 +1,7 @@
 cabal-version:      3.0
 
 name:               phino
-version:            0.0.0.35
+version:            0.0.0.36
 license:            MIT
 synopsis:           Command-Line Manipulator of 𝜑-Calculus Expressions
 description:        Please see the README on GitHub at <https://github.com/objectionary/phino#readme>
diff --git a/src/Functions.hs b/src/Functions.hs
--- a/src/Functions.hs
+++ b/src/Functions.hs
@@ -17,7 +17,7 @@
 import Matcher
 import Misc
 import Numeric (showHex)
-import Parser (parseAttributeThrows)
+import Parser (parseAttributeThrows, parseNumberThrows)
 import Pretty
 import Random (randomString)
 import Regexp
@@ -163,4 +163,12 @@
   attr' <- buildAttributeThrows attr subst
   pure (TeExpression (DataString (strToBts (prettyAttribute attr'))))
 buildTermFromFunction "string" _ _ _ = throwIO (userError "Function string() requires exactly 1 argument as attribute or data expression (Φ̇.number or Φ̇.string)")
+buildTermFromFunction "number" [Y.ArgExpression expr] subst _ = do
+  (expr', _) <- buildExpressionThrows expr subst
+  case expr' of
+    DataString bts -> do
+      num <- parseNumberThrows (btsToUnescapedStr bts)
+      pure (TeExpression num)
+    _ -> throwIO (userError (printf "Function number() expects expression to be 'Φ̇.string', but got:\n%s" (prettyExpression' expr')))
+buildTermFromFunction "number" _ _ _ = throwIO (userError "Function number() requires exactly 1 argument as 'Φ̇.string'")
 buildTermFromFunction func _ _ _ = throwIO (userError (printf "Function %s() is not supported or does not exist" func))
diff --git a/src/Misc.hs b/src/Misc.hs
--- a/src/Misc.hs
+++ b/src/Misc.hs
@@ -239,6 +239,8 @@
 -- "hello"
 -- >>> btsToStr (BtOne "68")
 -- "h"
+-- >>> btsToStr (BtOne "35")
+-- "5"
 -- >>> btsToStr (BtMany ["77", "6F", "72", "6C", "64"])
 -- "world"
 -- >>> btsToStr BtEmpty
@@ -268,6 +270,8 @@
 -- "world"
 -- >>> btsToUnescapedStr (BtMany ["68", "22"])
 -- "h\""
+-- >>> btsToUnescapedStr (BtOne "35")
+-- "5"
 btsToUnescapedStr :: Bytes -> String
 btsToUnescapedStr bytes = T.unpack (T.decodeUtf8 (B.pack (btsToWord8 bytes)))
 
diff --git a/src/Parser.hs b/src/Parser.hs
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -12,6 +12,8 @@
     parseExpressionThrows,
     parseAttribute,
     parseAttributeThrows,
+    parseNumber,
+    parseNumberThrows,
     parseBinding,
     parseBytes,
   )
@@ -39,12 +41,14 @@
   = CouldNotParseProgram {message :: String}
   | CouldNotParseExpression {message :: String}
   | CouldNotParseAttribute {message :: String}
+  | CouldNotParseNumber {message :: String}
   deriving (Exception)
 
 instance Show ParserException where
   show CouldNotParseProgram {..} = printf "Couldn't parse given phi program, cause: %s" message
-  show CouldNotParseExpression {..} = printf "Couldn't parse given phi program, cause: %s" message
+  show CouldNotParseExpression {..} = printf "Couldn't parse given phi expression, cause: %s" message
   show CouldNotParseAttribute {..} = printf "Couldn't parse given attribute, cause: %s" message
+  show CouldNotParseNumber {..} = printf "Couldn't parse given number to 'Φ̇.number', cause: %s" message
 
 -- White space consumer
 whiteSpace :: Parser ()
@@ -202,6 +206,18 @@
         <?> "bytes"
     )
 
+number :: Parser Expression
+number = do
+  sign <- optional (choice [char '-', char '+'])
+  unsigned <- lexeme L.scientific
+  let num =
+        toRealFloat
+          ( case sign of
+              Just '-' -> negate unsigned
+              _ -> unsigned
+          )
+  return (DataNumber (numToBts num))
+
 tauBinding :: Parser Attribute -> Parser Binding
 tauBinding attr = do
   attr' <- attr
@@ -329,16 +345,7 @@
       do
         _ <- choice [symbol "T", symbol "⊥"]
         return ExTermination,
-      do
-        sign <- optional (choice [char '-', char '+'])
-        unsigned <- lexeme L.scientific
-        let num =
-              toRealFloat
-                ( case sign of
-                    Just '-' -> negate unsigned
-                    _ -> unsigned
-                )
-        return (DataNumber (numToBts num)),
+      number,
       lexeme $ do
         _ <- char '"'
         str <- manyTill (choice [escapedChar, noneOf ['\\', '"']]) (char '"')
@@ -437,6 +444,14 @@
 
 parseBinding :: String -> Either String Binding
 parseBinding = parse' "binding" binding
+
+parseNumber :: String -> Either String Expression
+parseNumber = parse' "number" number
+
+parseNumberThrows :: String -> IO Expression
+parseNumberThrows num = case parseNumber num of
+  Right num' -> pure num'
+  Left err -> throwIO (CouldNotParseNumber err)
 
 parseAttribute :: String -> Either String Attribute
 parseAttribute = parse' "attribute" fullAttribute