diff --git a/gaboshlib/g_num_is_approx.sh b/gaboshlib/g_num_is_approx.sh
new file mode 100644
index 0000000..3b5ebf7
--- /dev/null
+++ b/gaboshlib/g_num_is_approx.sh
@@ -0,0 +1,17 @@
+function g_num_is_approx {
+  
+  # check if $1 is in percentage range ($3 and $4) to $2
+  local f_num=$1
+  local f_base=$2
+  local f_percentage_up=$3
+  local f_percentage_down=$4
+
+  # Check for valid decimal number
+  
+  g_num_valid_number "${f_num}" "${f_base}" "${f_percentage_up}" "${f_percentage_down}" || return 1
+ 
+  local f_from=$(echo "${f_base} - (${f_base} / 100 * ${f_percentage_down})" | bc -l)
+  local f_to=$(echo "${f_base} + (${f_base} / 100 * ${f_percentage_up})" | bc -l)
+
+  g_num_is_between ${f_num} ${f_from} ${f_to}
+}