diff --git a/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt b/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt
deleted file mode 100644
index cc4424ea..00000000
--- a/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt
+++ /dev/null
@@ -1,14 +0,0 @@
-package net.dankito.utils.multiplatform
-
-import kotlin.String
-
-
-expect class StringHelper {
-
-    companion object {
-
-        fun format(format: String, vararg args: Any?): String
-
-    }
-
-}
\ No newline at end of file
diff --git a/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/NumberExtensions.kt b/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/NumberExtensions.kt
index b905bb03..afb5360b 100644
--- a/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/NumberExtensions.kt
+++ b/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/NumberExtensions.kt
@@ -1,16 +1,26 @@
 package net.dankito.utils.multiplatform.extensions
 
-import net.dankito.utils.multiplatform.StringHelper
-
 
 fun Int.toStringWithTwoDigits(): String {
   return toStringWithMinDigits(2)
 }
 
-fun Int.toStringWithMinDigits(countDigits: Int): String {
-  return format("%0${countDigits}d")
+fun Int.toStringWithMinDigits(minimumCountDigits: Int): String {
+  val countDigitsToAdd = minimumCountDigits - this.numberOfDigits
+  val prefix = if (countDigitsToAdd > 0) "0".repeat(countDigitsToAdd) else ""
+
+  return prefix + this.toString()
 }
 
-fun Int.format(format: String): String {
-  return StringHelper.format(format, this)
-}
\ No newline at end of file
+val Int.numberOfDigits: Int
+  get() {
+    var number = this
+    var count = 0
+
+    while (number != 0) {
+      number /= 10
+      ++count
+    }
+
+    return count
+  }
\ No newline at end of file
diff --git a/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/StringExtensions.kt b/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/StringExtensions.kt
deleted file mode 100644
index a1591931..00000000
--- a/multiplatform-utils/src/commonMain/kotlin/net/dankito/utils/multiplatform/extensions/StringExtensions.kt
+++ /dev/null
@@ -1,8 +0,0 @@
-package net.dankito.utils.multiplatform.extensions
-
-import net.dankito.utils.multiplatform.StringHelper
-
-
-fun String.format(vararg args: Any?): String {
-  return StringHelper.format(this, args)
-}
\ No newline at end of file
diff --git a/multiplatform-utils/src/commonTest/kotlin/net.dankito.utils.multiplatform.extensions/NumberExtensionsTest.kt b/multiplatform-utils/src/commonTest/kotlin/net.dankito.utils.multiplatform.extensions/NumberExtensionsTest.kt
new file mode 100644
index 00000000..cc659368
--- /dev/null
+++ b/multiplatform-utils/src/commonTest/kotlin/net.dankito.utils.multiplatform.extensions/NumberExtensionsTest.kt
@@ -0,0 +1,86 @@
+import net.dankito.utils.multiplatform.extensions.numberOfDigits
+import net.dankito.utils.multiplatform.extensions.toStringWithMinDigits
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class NumberExtensionsTest {
+
+  @Test
+  fun toStringWithMinDigits_0() {
+    val result = 7.toStringWithMinDigits(0)
+
+    assertEquals("7", result)
+  }
+
+  @Test
+  fun toStringWithMinDigits_1() {
+    val result = 7.toStringWithMinDigits(1)
+
+    assertEquals("7", result)
+  }
+
+  @Test
+  fun toStringWithMinDigits_2() {
+    val result = 7.toStringWithMinDigits(2)
+
+    assertEquals("07", result)
+  }
+
+  @Test
+  fun toStringWithMinDigits_3() {
+    val result = 7.toStringWithMinDigits(3)
+
+    assertEquals("007", result)
+  }
+
+  @Test
+  fun toStringWithMinDigits_5() {
+    val result = 7.toStringWithMinDigits(5)
+
+    assertEquals("00007", result)
+  }
+
+  @Test
+  fun toStringWithMinDigits_10() {
+    val result = 7.toStringWithMinDigits(10)
+
+    assertEquals("0000000007", result)
+  }
+
+
+  @Test
+  fun getNumberOfDigits_0() {
+    val result = 0.numberOfDigits
+
+    assertEquals(0, result)
+  }
+
+  @Test
+  fun getNumberOfDigits_1Digit() {
+    val result = 7.numberOfDigits
+
+    assertEquals(1, result)
+  }
+
+  @Test
+  fun getNumberOfDigits_2Digits() {
+    val result = 42.numberOfDigits
+
+    assertEquals(2, result)
+  }
+
+  @Test
+  fun getNumberOfDigits_3Digits() {
+    val result = 123.numberOfDigits
+
+    assertEquals(3, result)
+  }
+
+  @Test
+  fun getNumberOfDigits_10Digits() {
+    val result = 1234567890.numberOfDigits
+
+    assertEquals(10, result)
+  }
+
+}
\ No newline at end of file
diff --git a/multiplatform-utils/src/iosMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt b/multiplatform-utils/src/iosMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt
deleted file mode 100644
index 619ff309..00000000
--- a/multiplatform-utils/src/iosMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt
+++ /dev/null
@@ -1,40 +0,0 @@
-package net.dankito.utils.multiplatform
-
-import kotlin.String
-import platform.Foundation.*
-
-
-actual class StringHelper {
-
-    actual companion object {
-
-        actual fun format(format: String, vararg args: Any?): String {
-            val adjustedFormat = format.replace("%s", "%@") // Objective-C uses %@ for strings // TODO: also replace %$1s, ...
-
-//            return NSString.stringWithFormat("%@ %@ %d", "один" as NSString, "two" as NSString, 3)
-            //return NSString.stringWithFormat(adjustedFormat, args.firstOrNull()) // spread operator is not supported for varadic functions, seehttps://github.com/JetBrains/kotlin-native/issues/1834
-
-            // as spread operator is not supported for varadic functions tried to pass arguments one by one, but didn't work either
-            return when (args.size) {
-                0 -> format
-                1 -> format(adjustedFormat, args.first())
-                2 -> format(adjustedFormat, args.first(), args.get(2))
-                else -> format(adjustedFormat, args.first(), args.get(2), args.get(3))
-            }
-        }
-
-        fun format(format: String, arg1: Any): String {
-            return NSString.stringWithFormat(format, arg1 as? NSString ?: arg1)
-        }
-
-        fun format(format: String, arg1: Any, arg2: Any): String {
-            return NSString.stringWithFormat(format, arg1 as? NSString ?: arg1, arg2 as? NSString ?: arg2)
-        }
-
-        fun format(format: String, arg1: Any, arg2: Any, arg3: Any): String {
-            return NSString.stringWithFormat(format, arg1 as? NSString ?: arg1, arg2 as? NSString ?: arg2, arg3 as? NSString ?: arg3)
-        }
-
-    }
-
-}
\ No newline at end of file
diff --git a/multiplatform-utils/src/jvmMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt b/multiplatform-utils/src/jvmMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt
deleted file mode 100644
index a9df9b58..00000000
--- a/multiplatform-utils/src/jvmMain/kotlin/net/dankito/utils/multiplatform/StringHelper.kt
+++ /dev/null
@@ -1,16 +0,0 @@
-package net.dankito.utils.multiplatform
-
-import kotlin.String
-
-
-actual class StringHelper {
-
-    actual companion object {
-
-        actual fun format(format: String, vararg args: Any?): String {
-            return String.format(format, *args)
-        }
-
-    }
-
-}
\ No newline at end of file