diff --git a/build.gradle.kts b/build.gradle.kts
index 08780a4..cb2df04 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -20,7 +20,7 @@ tasks.test {
 }
 
 kotlin {
-    jvmToolchain(11)
+    jvmToolchain(17)
 }
 
 detekt {
diff --git a/src/main/kotlin/mate/academy/NumberTransformation.kt b/src/main/kotlin/mate/academy/NumberTransformation.kt
index 27818c6..d22e56e 100644
--- a/src/main/kotlin/mate/academy/NumberTransformation.kt
+++ b/src/main/kotlin/mate/academy/NumberTransformation.kt
@@ -6,6 +6,13 @@ package mate.academy
     If the number is not present return null
  */
 
-fun getReminder(numberStr: String?) : Int? {
-    return null
+private const val MULTIPLIER = 3
+private const val ADDITION_VALUE = 10
+private const val DIVISOR = 11
+
+fun getReminder(numberStr: String?): Int? {
+    return numberStr?.toInt()
+        ?.times(MULTIPLIER)
+        ?.plus(ADDITION_VALUE)
+        ?.rem(DIVISOR)
 }
diff --git a/src/main/kotlin/mate/academy/TotalPrice.kt b/src/main/kotlin/mate/academy/TotalPrice.kt
index d114745..5b7c1f9 100644
--- a/src/main/kotlin/mate/academy/TotalPrice.kt
+++ b/src/main/kotlin/mate/academy/TotalPrice.kt
@@ -1,9 +1,12 @@
 package mate.academy
 
+private const val DEFAULT_PRICE_PER_PRODUCT = 29.99
+
 /*
     Calculate the products total price based on the provide price per product and products amount.
     If the price is not provided, use default price per product equal to 29.99
  */
-fun calculateTotalPrice(pricePerProduct: Double?, count: Int) : Double {
-    return 0.0
+fun calculateTotalPrice(pricePerProduct: Double?, count: Int): Double {
+    val price = pricePerProduct ?: DEFAULT_PRICE_PER_PRODUCT
+    return price * count
 }