diff --git a/package.json b/package.json
index a3cfedc..7c6d0b6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ssf",
-  "version": "0.5.7",
+  "version": "0.5.8",
   "author": "SheetJS",
   "description": "pure-JS library to format data using ECMA-376 spreadsheet Format Codes",
   "keywords": [ "format", "sprintf", "spreadsheet" ],
diff --git a/ssf.js b/ssf.js
index 5114a21..829f3eb 100644
--- a/ssf.js
+++ b/ssf.js
@@ -5,7 +5,7 @@ var _strrev = function(x) { return String(x).split("").reverse().join("");};
 function fill(c,l) { return new Array(l+1).join(c); }
 function pad(v,d,c){var t=String(v);return t.length>=d?t:(fill(c||0,d-t.length)+t);}
 function rpad(v,d,c){var t=String(v);return t.length>=d?t:(t+fill(c||0,d-t.length));}
-SSF.version = '0.5.7';
+SSF.version = '0.5.8';
 /* Options */
 var opts_fmt = {};
 function fixopts(o){for(var y in opts_fmt) if(o[y]===undefined) o[y]=opts_fmt[y];}
@@ -112,7 +112,7 @@ var general_fmt = function(v) {
     return o.replace("e","E").replace(/\.0*$/,"").replace(/\.([0-9]*[^0])0*$/,".$1").replace(/(E[+-])([0-9])$/,"$1"+"0"+"$2");
   }
   if(typeof v === 'string') return v;
-  throw "unsupported value in General format: " + v;
+  throw new Error("unsupported value in General format: " + v);
 };
 SSF._general = general_fmt;
 var parse_date_code = function parse_date_code(v,opts) {
@@ -229,7 +229,7 @@ var write_num = function(type, fmt, val) {
     return o.replace("e","E");
   }
   if(fmt[0] === "$") return "$"+write_num(type,fmt.substr(fmt[1]==' '?2:1),val);
-  var r, ff, aval = val < 0 ? -val : val, sign = val < 0 ? "-" : "";
+  var r, rr, ff, aval = val < 0 ? -val : val, sign = val < 0 ? "-" : "";
   if((r = fmt.match(/# (\?+)([ ]?)\/([ ]?)(\d+)/))) {
     var den = Number(r[4]), rnd = Math.round(aval * den), base = Math.floor(rnd/den);
     var myn = (rnd - base*den), myd = den;
@@ -242,8 +242,17 @@ var write_num = function(type, fmt, val) {
     o = Math.round(val * Math.pow(10,r[1].length));
     return String(o/Math.pow(10,r[1].length)).replace(/^([^\.]+)$/,"$1."+r[1]).replace(/\.$/,"."+r[1]).replace(/\.([0-9]*)$/,function($$, $1) { return "." + $1 + fill("0", r[1].length-$1.length); });
   }
+  if((r = fmt.match(/^(0*)\.(#*)$/))) {
+    o = Math.round(val*Math.pow(10,r[2].length));
+    return String(o * Math.pow(10,-r[2].length)).replace(/\.(\d*[1-9])0*$/,".$1").replace(/^([-]?\d*)$/,"$1.").replace(/^0\./,r[1].length?"0.":".");
+  }
+  if((r = fmt.match(/^#,##0([.]?)$/))) return sign + commaify(String(Math.round(aval)));
+  if((r = fmt.match(/^#,##0\.([#0]*0)$/))) {
+    rr = Math.round((val-Math.floor(val))*Math.pow(10,r[1].length));
+    return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(rr,r[1].length,0);
+  }
   if((r = fmt.match(/^# ([?]+)([ ]?)\/([ ]?)([?]+)/))) {
-    var rr = Math.min(Math.max(r[1].length, r[4].length),7);
+    rr = Math.min(Math.max(r[1].length, r[4].length),7);
     ff = frac(aval, Math.pow(10,rr)-1, true);
     return sign + (ff[0]||(ff[1] ? "" : "0")) + " " + (ff[1] ? pad(ff[1],rr," ") + r[2] + "/" + r[3] + rpad(ff[2],rr," "): fill(" ", 2*rr+1 + r[2].length + r[3].length));
   }
@@ -252,16 +261,6 @@ var write_num = function(type, fmt, val) {
     case "#.##": o = Math.round(val*100);
       return String(o/100).replace(/^([^\.]+)$/,"$1.").replace(/^0\.$/,".");
     case "#,###": var x = commaify(String(Math.round(aval))); return x !== "0" ? sign + x : "";
-    case "#,##0": return sign + commaify(String(Math.round(aval)));
-    case "#,##0.0": r = Math.round((val-Math.floor(val))*10); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,1,"0");
-    case "#,##0.00": r = Math.round((val-Math.floor(val))*100); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,2,"0");
-    case "#,##0.000": r = Math.round((val-Math.floor(val))*1000); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,3,0);
-    case "#,##0.0000": r = Math.round((val-Math.floor(val))*10000); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,4,0);
-    case "#,##0.00000": r = Math.round((val-Math.floor(val))*Math.pow(10,5)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,5,0);
-    case "#,##0.000000": r = Math.round((val-Math.floor(val))*Math.pow(10,6)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,6,0);
-    case "#,##0.0000000": r = Math.round((val-Math.floor(val))*Math.pow(10,7)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,7,0);
-    case "#,##0.00000000": r = Math.round((val-Math.floor(val))*Math.pow(10,8)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,8,0);
-    case "#,##0.000000000": r = Math.round((val-Math.floor(val))*Math.pow(10,9)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,9,0);
     default:
   }
   throw new Error("unsupported format |" + fmt + "|");
@@ -278,7 +277,7 @@ function split_fmt(fmt) {
     j = i+1;
   }
   out.push(fmt.slice(j));
-  if(in_str !=-1) throw "Format |" + fmt + "| unterminated string at " + in_str;
+  if(in_str !=-1) throw new Error("Format |" + fmt + "| unterminated string at " + in_str);
   return out;
 }
 SSF._split = split_fmt;
@@ -291,7 +290,7 @@ function eval_fmt(fmt, v, opts, flen) {
     switch((c = fmt[i])) {
       case 'G': /* General */
         if(fmt.substr(i, i+6).toLowerCase() !== "general")
-          throw 'unrecognized character ' + fmt[i] + ' in ' + fmt;
+          throw new Error('unrecognized character ' + fmt[i] + ' in ' +fmt);
         out.push({t:'G',v:'General'}); i+=7; break;
       case '"': /* Literal text */
         for(o="";fmt[++i] !== '"' && i < fmt.length;) o += fmt[i];
@@ -334,7 +333,7 @@ function eval_fmt(fmt, v, opts, flen) {
         } else { o=""; }
         break;
       /* Numbers */
-      case '0': case '#':
+      case '0': case '#': case '.':
         o = c; while("0#?.,E+-%".indexOf(c=fmt[++i]) > -1) o += c;
         out.push({t:'n', v:o}); break;
       case '?':
diff --git a/ssf.md b/ssf.md
index bf05817..c61c856 100644
--- a/ssf.md
+++ b/ssf.md
@@ -76,7 +76,7 @@ function split_fmt(fmt) {
     j = i+1;
   }
   out.push(fmt.slice(j));
-  if(in_str !=-1) throw "Format |" + fmt + "| unterminated string at " + in_str;
+  if(in_str !=-1) throw new Error("Format |" + fmt + "| unterminated string at " + in_str);
   return out;
 }
 SSF._split = split_fmt;
@@ -168,7 +168,7 @@ For strings, just return the text as-is:
 Anything else is bad:
 
 ```
-  throw "unsupported value in General format: " + v;
+  throw new Error("unsupported value in General format: " + v);
 };
 SSF._general = general_fmt;
 ```
@@ -413,7 +413,7 @@ TODO: localize the currency:
 Fractions with known denominator are resolved by rounding:
 
 ```js>tmp/60_number.js
-  var r, ff, aval = val < 0 ? -val : val, sign = val < 0 ? "-" : "";
+  var r, rr, ff, aval = val < 0 ? -val : val, sign = val < 0 ? "-" : "";
   if((r = fmt.match(/# (\?+)([ ]?)\/([ ]?)(\d+)/))) {
     var den = Number(r[4]), rnd = Math.round(aval * den), base = Math.floor(rnd/den);
     var myn = (rnd - base*den), myd = den;
@@ -431,13 +431,22 @@ A few special general cases can be handled in a very dumb manner:
     o = Math.round(val * Math.pow(10,r[1].length));
     return String(o/Math.pow(10,r[1].length)).replace(/^([^\.]+)$/,"$1."+r[1]).replace(/\.$/,"."+r[1]).replace(/\.([0-9]*)$/,function($$, $1) { return "." + $1 + fill("0", r[1].length-$1.length); });
   }
+  if((r = fmt.match(/^(0*)\.(#*)$/))) {
+    o = Math.round(val*Math.pow(10,r[2].length));
+    return String(o * Math.pow(10,-r[2].length)).replace(/\.(\d*[1-9])0*$/,".$1").replace(/^([-]?\d*)$/,"$1.").replace(/^0\./,r[1].length?"0.":".");
+  }
+  if((r = fmt.match(/^#,##0([.]?)$/))) return sign + commaify(String(Math.round(aval)));
+  if((r = fmt.match(/^#,##0\.([#0]*0)$/))) {
+    rr = Math.round((val-Math.floor(val))*Math.pow(10,r[1].length));
+    return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(rr,r[1].length,0);
+  }
 ```
 
 The frac helper function is used for fraction formats (defined below).
 
 ```
   if((r = fmt.match(/^# ([?]+)([ ]?)\/([ ]?)([?]+)/))) {
-    var rr = Math.min(Math.max(r[1].length, r[4].length),7);
+    rr = Math.min(Math.max(r[1].length, r[4].length),7);
     ff = frac(aval, Math.pow(10,rr)-1, true);
     return sign + (ff[0]||(ff[1] ? "" : "0")) + " " + (ff[1] ? pad(ff[1],rr," ") + r[2] + "/" + r[3] + rpad(ff[2],rr," "): fill(" ", 2*rr+1 + r[2].length + r[3].length));
   }
@@ -451,16 +460,6 @@ The default cases are hard-coded.  TODO: actually parse them
     case "#.##": o = Math.round(val*100);
       return String(o/100).replace(/^([^\.]+)$/,"$1.").replace(/^0\.$/,".");
     case "#,###": var x = commaify(String(Math.round(aval))); return x !== "0" ? sign + x : "";
-    case "#,##0": return sign + commaify(String(Math.round(aval)));
-    case "#,##0.0": r = Math.round((val-Math.floor(val))*10); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,1,"0");
-    case "#,##0.00": r = Math.round((val-Math.floor(val))*100); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,2,"0");
-    case "#,##0.000": r = Math.round((val-Math.floor(val))*1000); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,3,0);
-    case "#,##0.0000": r = Math.round((val-Math.floor(val))*10000); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,4,0);
-    case "#,##0.00000": r = Math.round((val-Math.floor(val))*Math.pow(10,5)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,5,0);
-    case "#,##0.000000": r = Math.round((val-Math.floor(val))*Math.pow(10,6)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,6,0);
-    case "#,##0.0000000": r = Math.round((val-Math.floor(val))*Math.pow(10,7)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,7,0);
-    case "#,##0.00000000": r = Math.round((val-Math.floor(val))*Math.pow(10,8)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,8,0);
-    case "#,##0.000000000": r = Math.round((val-Math.floor(val))*Math.pow(10,9)); return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(r,9,0);
 ```
 
 For now, the default case is an error:
@@ -489,7 +488,7 @@ LO Formats sometimes leak "GENERAL" or "General" to stand for general format:
 ```
       case 'G': /* General */
         if(fmt.substr(i, i+6).toLowerCase() !== "general")
-          throw 'unrecognized character ' + fmt[i] + ' in ' + fmt;
+          throw new Error('unrecognized character ' + fmt[i] + ' in ' +fmt);
         out.push({t:'G',v:'General'}); i+=7; break;
 ```
 
@@ -603,7 +602,7 @@ Number blocks (following the general pattern `[0#?][0#?.,E+-%]*`) are grouped to
 
 ```
       /* Numbers */
-      case '0': case '#':
+      case '0': case '#': case '.':
         o = c; while("0#?.,E+-%".indexOf(c=fmt[++i]) > -1) o += c;
         out.push({t:'n', v:o}); break;
 
@@ -997,7 +996,7 @@ coveralls:
 ```json>package.json
 {
   "name": "ssf",
-  "version": "0.5.7",
+  "version": "0.5.8",
   "author": "SheetJS",
   "description": "pure-JS library to format data using ECMA-376 spreadsheet Format Codes",
   "keywords": [ "format", "sprintf", "spreadsheet" ],
diff --git a/test/oddities.json b/test/oddities.json
index 2d83dc4..f277e6c 100644
--- a/test/oddities.json
+++ b/test/oddities.json
@@ -45,5 +45,6 @@
   ["A/P", [0.7, "P"]],
   ["e", [0.7, "1900"]],
   ["123", [0.7, "123"], [0, "123"], ["sheetjs", "sheetjs"]],
+  ["0.##", [1,"1."], [-1,"-1."], [0, "0."], [1.1, "1.1"], [-1.2, "-1.2"], [1000000000000.01, "1000000000000.01"], [-1000.01, "-1000.01"], [0.1, "0.1"], [1.007, "1.01"], [-1.008, "-1.01"]],
   ["\"foo\";\"bar\";\"baz\";\"qux\";\"foobar\"", [1], [0], [-1], ["sheetjs"]]
 ]