diff --git a/src/client.ts b/src/client.ts
index 3a451ba..fe9e022 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -54,7 +54,7 @@ export default class Comcigan {
     const data = parseResponse(res.data)
 
     const teachers = data[`자료${teacherCode}`] as string[]
-    const teachersLen = log10int(teachers.length - 1) + 1
+    const teachersLen = Math.floor(Math.log10(teachers.length - 1)) + 1
     const subjects = data[`자료${subjectCode}`] as string[]
 
     return (data[`자료${dayCode}`] as number[][][][]).slice(1).map((grade) =>
diff --git a/src/utils/math.ts b/src/utils/math.ts
deleted file mode 100644
index 20f2611..0000000
--- a/src/utils/math.ts
+++ /dev/null
@@ -1 +0,0 @@
-export const log10int = (n: number) => Math.floor(Math.log10(n))