From 263826852c2c6e6d42a8ee5cd3095d2168e35e20 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Fri, 27 Mar 2026 00:22:08 +0100
Subject: [PATCH 1/3] [add] exception when rounding "0" to figures

Always return "0" without fractional
---
 src/rounding.typ        | 13 ++++++++-----
 tests/rounding/test.typ | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/rounding.typ b/src/rounding.typ
index 43c45ac..8cd4428 100644
--- a/src/rounding.typ
+++ b/src/rounding.typ
@@ -98,15 +98,18 @@
 /// 
 /// The result is never negative. 
 #let get-rounding-digit(int, frac, mode, precision) = {
-  let round-digit = precision + if mode == "places" {
-    int.len()
+  if mode == "places" {
+    precision + int.len()
   } else if mode == "figures" {
-    count-leading-zeros(int + frac)
+    if (int + frac).trim("0") == "" {
+      int.len()
+    } else {
+      precision + count-leading-zeros(int + frac)
+    }
   }
-
-  calc.max(round-digit)
 }
 
+
 /// Pads a decimal number to given precision with given rounding mode. 
 /// Examples with `pad: true`:
 /// - `62.1` (`"62", "1"`), `mode: "places", precision: 2`
diff --git a/tests/rounding/test.typ b/tests/rounding/test.typ
index ecc6265..e4e85af 100644
--- a/tests/rounding/test.typ
+++ b/tests/rounding/test.typ
@@ -258,3 +258,22 @@
   ),
   ("1", "23", (("", "04"), ("", "30"))),
 )
+#assert.eq(
+  round(
+    "0",
+    "",
+    precision: 2,
+    mode: "places",
+  ),
+  ("", "00", none),
+)
+
+#assert.eq(
+  round(
+    "0",
+    "",
+    precision: 2,
+    mode: "figures",
+  ),
+  ("", "", none),
+)

From a6204e58aec84b398d95023493272bc614ee8344 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Fri, 27 Mar 2026 09:44:51 +0100
Subject: [PATCH 2/3] [change] Add no exponent with sci/eng if number is 0

---
 src/num.typ                    | 6 ++++++
 tests/num/engineering/ref.typ  | 7 ++++++-
 tests/num/engineering/test.typ | 5 +++++
 tests/num/scientific/ref.typ   | 8 +++++++-
 tests/num/scientific/test.typ  | 6 ++++++
 5 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/num.typ b/src/num.typ
index 02a51c5..963338d 100644
--- a/src/num.typ
+++ b/src/num.typ
@@ -34,6 +34,12 @@
 
 // Process the exponent with its various modes mode
 #let process-exponent(info, exponent) = {
+
+  if (info.int + info.frac).trim("0") == "" {
+    // Add no exponent if number is 0
+    return info
+  }
+
   let new-exponent = if type(exponent) == dictionary {
     assert(
       "fixed" in exponent or "sci" in exponent,
diff --git a/tests/num/engineering/ref.typ b/tests/num/engineering/ref.typ
index eb8ce38..83ff46f 100644
--- a/tests/num/engineering/ref.typ
+++ b/tests/num/engineering/ref.typ
@@ -15,4 +15,9 @@ $10×10^(-3)$ \
 $1×10^(-3)$ \
 $100×10^(-6)$ \
 $10×10^(-6)$ \
-$1×10^(-6)$ \
\ No newline at end of file
+$1×10^(-6)$ \
+
+#pagebreak()
+
+$0$ \
+$0×10^2$ \
diff --git a/tests/num/engineering/test.typ b/tests/num/engineering/test.typ
index 4501f99..bdbe3a8 100644
--- a/tests/num/engineering/test.typ
+++ b/tests/num/engineering/test.typ
@@ -19,3 +19,8 @@
 #num(exponent: "eng")[.0001] \
 #num(exponent: "eng")[.00001] \
 #num(exponent: "eng")[1e-6] \
+
+#pagebreak()
+
+#num(exponent: "eng")[0] \
+#num(exponent: "eng")[0e2] \ // it's okay that the exponent is now 2
diff --git a/tests/num/scientific/ref.typ b/tests/num/scientific/ref.typ
index 07ebc80..cfa4caf 100644
--- a/tests/num/scientific/ref.typ
+++ b/tests/num/scientific/ref.typ
@@ -1,7 +1,7 @@
 #set page(width: auto, height: auto, margin: .5em)
 
 $1.23×10^2$ \
-$1.2×10^11$
+$1.2×10^11$ \
 
 #pagebreak()
 
@@ -16,3 +16,9 @@ $120$ \
 $1.200×10^3$ \
 $0.001$ \
 $1×10^(-4)$ \
+
+#pagebreak()
+
+$0$ \
+$0×10^4$ \
+$0.00$ \
diff --git a/tests/num/scientific/test.typ b/tests/num/scientific/test.typ
index 7817e7d..6f95222 100644
--- a/tests/num/scientific/test.typ
+++ b/tests/num/scientific/test.typ
@@ -19,3 +19,9 @@
 #num(exponent: (sci: (-4, 3)))[1200] \
 #num(exponent: (sci: (-4, 3)))[.001] \
 #num(exponent: (sci: (-4, 3)))[.0001] \
+
+#pagebreak()
+
+#num(exponent: "sci")[0] \
+#num(exponent: "sci")[0e4] \
+#num(exponent: "sci")[0.00] \

From e4ff8cb814e929380d2b4aee45f930bf53034663 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Fri, 27 Mar 2026 11:44:34 +0100
Subject: [PATCH 3/3] [add] tests

---
 tests/num/fixed/ref.typ         |  3 ++-
 tests/num/fixed/test.typ        |  1 +
 tests/num/trim-zeros/.gitignore |  5 +++++
 tests/rounding/ref.typ          | 14 ++++++++++++++
 tests/rounding/test.typ         | 23 +++++++++++++++++++++++
 5 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 tests/num/trim-zeros/.gitignore
 create mode 100644 tests/rounding/ref.typ

diff --git a/tests/num/fixed/ref.typ b/tests/num/fixed/ref.typ
index ce99aa5..1ca14bd 100644
--- a/tests/num/fixed/ref.typ
+++ b/tests/num/fixed/ref.typ
@@ -7,4 +7,5 @@ $0.1234×10^1$ \
 $1000×10^1$ \
 $0.001×10^(-1)$ \
 $(0.2 plus.minus 0.1)×10^1$ \
-$(0.2 plus.minus 0.1)×10^2$ 
+$(0.2 plus.minus 0.1)×10^2$ \
+$0.00$ \
diff --git a/tests/num/fixed/test.typ b/tests/num/fixed/test.typ
index b7592b4..0d57a58 100644
--- a/tests/num/fixed/test.typ
+++ b/tests/num/fixed/test.typ
@@ -11,3 +11,4 @@
 #num(exponent: (fixed: -1))[1e-4] \
 #num(exponent: (fixed: 1))[2+-1] \
 #num(exponent: (fixed: 2))[2+-1e1] \
+#num(exponent: (fixed: 2))[0.00] \
diff --git a/tests/num/trim-zeros/.gitignore b/tests/num/trim-zeros/.gitignore
new file mode 100644
index 0000000..2e4c5d8
--- /dev/null
+++ b/tests/num/trim-zeros/.gitignore
@@ -0,0 +1,5 @@
+# generated by tytanic, do not edit
+
+/diff/
+/out/
+/ref/
diff --git a/tests/rounding/ref.typ b/tests/rounding/ref.typ
new file mode 100644
index 0000000..17c3051
--- /dev/null
+++ b/tests/rounding/ref.typ
@@ -0,0 +1,14 @@
+
+#set page(width: auto, height: auto, margin: .5em)
+
+
+$0.000$ \
+$0.000$ \
+$0$ \
+$0.000$ \
+
+#pagebreak()
+
+$423.4×10^2$ \
+$4.2×10^4$ \
+$42×10^3$ \
diff --git a/tests/rounding/test.typ b/tests/rounding/test.typ
index e4e85af..f85f9d5 100644
--- a/tests/rounding/test.typ
+++ b/tests/rounding/test.typ
@@ -1,4 +1,5 @@
 #import "/src/rounding.typ": *
+#import "/src/zero.typ": num
 
 
 
@@ -277,3 +278,25 @@
   ),
   ("", "", none),
 )
+
+
+
+
+
+
+#set page(width: auto, height: auto, margin: .5em)
+
+// Rounding zero
+#num(round: (precision: 3, mode: "places"))[0] \
+#num(round: (precision: 3, mode: "places"))[0.0] \
+#num(round: (precision: 3, mode: "figures"))[0] \
+#num(round: (precision: 3, mode: "places"), exponent: "sci")[0.0]
+
+#pagebreak()
+
+// Rounding affects displayed digits, (after the exponent is applied)
+#num(round: (precision: 1), exponent: (fixed: 2))[42.34e3] \
+#num(round: (precision: 1), exponent: "sci")[42.34e3] \
+#num(round: (precision: 2, mode: "figures"), exponent: "eng")[42.34e3] \
+
+