diff --git a/src/imcflibs/imagej/misc.py b/src/imcflibs/imagej/misc.py
index 7b9d2630..5496e7e3 100644
--- a/src/imcflibs/imagej/misc.py
+++ b/src/imcflibs/imagej/misc.py
@@ -123,7 +123,7 @@ def calculate_mean_and_stdv(values_list, round_decimals=0):
 
     mean = round(sum(filtered_list) / len(filtered_list), round_decimals)
     variance = sum((x - mean) ** 2 for x in filtered_list) / len(filtered_list)
-    std_dev = round(variance ** 0.5, round_decimals)
+    std_dev = round(variance**0.5, round_decimals)
 
     return mean, std_dev
 
@@ -627,31 +627,6 @@ def save_image_in_format(imp, format, out_dir, series, pad_number, split_channel
         current_imp.close()
 
 
-def pad_number(index, pad_length=2):
-    """Pad a number with leading zeros to a specified length.
-
-    Parameters
-    ----------
-    index : int or str
-        The number to be padded
-    pad_length : int, optional
-        The total length of the resulting string after padding, by default 2
-
-    Returns
-    -------
-    str
-        The padded number as a string
-
-    Examples
-    --------
-    >>> pad_number(7)
-    '07'
-    >>> pad_number(42, 4)
-    '0042'
-    """
-    return str(index).zfill(pad_length)
-
-
 def locate_latest_imaris(paths_to_check=None):
     """Find paths to latest installed Imaris or ImarisFileConverter version.
 
diff --git a/src/imcflibs/strtools.py b/src/imcflibs/strtools.py
index 10e731a6..d522c460 100644
--- a/src/imcflibs/strtools.py
+++ b/src/imcflibs/strtools.py
@@ -150,3 +150,28 @@ def alphanum_key(key):
         return [convert(c) for c in re.split("([0-9]+)", key)]
 
     return sorted(data, key=alphanum_key)
+
+
+def pad_number(index, pad_length=2):
+    """Pad a number with leading zeros to a specified length.
+
+    Parameters
+    ----------
+    index : int or str
+        The number to be padded
+    pad_length : int, optional
+        The total length of the resulting string after padding, by default 2
+
+    Returns
+    -------
+    str
+        The padded number as a string
+
+    Examples
+    --------
+    >>> pad_number(7)
+    '07'
+    >>> pad_number(42, 4)
+    '0042'
+    """
+    return str(index).zfill(pad_length)