diff --git a/basics/src/main/java/ru/msu/vmk/NumberSample.java b/basics/src/main/java/ru/msu/vmk/NumberSample.java
index 9961ed3..0edd4f2 100644
--- a/basics/src/main/java/ru/msu/vmk/NumberSample.java
+++ b/basics/src/main/java/ru/msu/vmk/NumberSample.java
@@ -1,11 +1,21 @@
 package ru.msu.vmk;
 
 import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Arrays;
 
 public class NumberSample {
     public static BigDecimal[] split(BigDecimal amount, int n) {
         // разделить amount на n частей
         // если остается остаток, прибавить его к первому числу
-        return null;
+        BigDecimal dividedEqualAmount = amount.divide(new BigDecimal(n), 2, RoundingMode.DOWN)
+                                        .stripTrailingZeros().movePointRight(1).movePointLeft(1);
+        BigDecimal remainder = amount.subtract(dividedEqualAmount.multiply(new BigDecimal(n)));
+
+        BigDecimal[] result = new BigDecimal[n];
+        Arrays.fill(result, dividedEqualAmount);
+        result[0].add(remainder).stripTrailingZeros().movePointRight(1).movePointLeft(1);
+
+        return result;
     }
-}
+}
\ No newline at end of file
diff --git a/object-oriented-programming/src/main/java/ru/msu/vmk/NumberSample.java b/object-oriented-programming/src/main/java/ru/msu/vmk/NumberSample.java
new file mode 100644
index 0000000..0edd4f2
--- /dev/null
+++ b/object-oriented-programming/src/main/java/ru/msu/vmk/NumberSample.java
@@ -0,0 +1,21 @@
+package ru.msu.vmk;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Arrays;
+
+public class NumberSample {
+    public static BigDecimal[] split(BigDecimal amount, int n) {
+        // разделить amount на n частей
+        // если остается остаток, прибавить его к первому числу
+        BigDecimal dividedEqualAmount = amount.divide(new BigDecimal(n), 2, RoundingMode.DOWN)
+                                        .stripTrailingZeros().movePointRight(1).movePointLeft(1);
+        BigDecimal remainder = amount.subtract(dividedEqualAmount.multiply(new BigDecimal(n)));
+
+        BigDecimal[] result = new BigDecimal[n];
+        Arrays.fill(result, dividedEqualAmount);
+        result[0].add(remainder).stripTrailingZeros().movePointRight(1).movePointLeft(1);
+
+        return result;
+    }
+}
\ No newline at end of file
diff --git a/object-oriented-programming/src/main/java/ru/msu/vmk/Quantity.java b/object-oriented-programming/src/main/java/ru/msu/vmk/Quantity.java
index 6c1810e..659cae2 100644
--- a/object-oriented-programming/src/main/java/ru/msu/vmk/Quantity.java
+++ b/object-oriented-programming/src/main/java/ru/msu/vmk/Quantity.java
@@ -1,6 +1,8 @@
 package ru.msu.vmk;
 
 import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Objects;
 
 /**
  * По примеру класса {@link Money} реализовать класс Quantity:
@@ -13,11 +15,23 @@
  * <br/> - для проверки работы реализовать функцию main() или Unit-test
  */
 public class Quantity {
+
+    private BigDecimal amount;
+    private String unitOfMeasurement;
+
     /**
      * @param amount - сумма
      * @param unitOfMeasurement - единица измерения
      */
     public Quantity(BigDecimal amount, String unitOfMeasurement) {
+        if (amount == null) {
+            throw new IllegalArgumentException("amount cannot be null");
+        }
+        if (unitOfMeasurement == null || unitOfMeasurement.isBlank()) {
+            throw new IllegalArgumentException("units cannot be empty");
+        }
+        this.amount = amount.setScale(2, RoundingMode.HALF_EVEN);
+        this.unitOfMeasurement = unitOfMeasurement;
     }
 
     /**
@@ -25,7 +39,11 @@ public Quantity(BigDecimal amount, String unitOfMeasurement) {
      * @return {@link Quantity#amount}
      */
     public BigDecimal getAmount() {
-        return null;
+        return amount;
+    }
+
+    public void setAmount(BigDecimal amount) {
+        this.amount = amount;
     }
 
     /**
@@ -35,7 +53,9 @@ public BigDecimal getAmount() {
      * @return сумма чисел
      */
     public Quantity add(Quantity quantity) throws Exception {
-        return null;
+        validateEqualUnitOfMeasurement(quantity);
+        BigDecimal sum = this.amount.add(quantity.amount);
+        return new Quantity(sum, this.unitOfMeasurement);
     }
 
     /**
@@ -45,7 +65,9 @@ public Quantity add(Quantity quantity) throws Exception {
      * @return разность чисел
      */
     public Quantity subtract(Quantity quantity) throws Exception {
-        return null;
+        validateEqualUnitOfMeasurement(quantity);
+        BigDecimal diff = this.amount.subtract(quantity.amount);
+        return new Quantity(diff, this.unitOfMeasurement);
     }
 
     /**
@@ -55,7 +77,9 @@ public Quantity subtract(Quantity quantity) throws Exception {
      * @return произведение
      */
     public Quantity multiply(Quantity quantity) throws Exception {
-        return null;
+        validateEqualUnitOfMeasurement(quantity);
+        BigDecimal result = this.amount.multiply(quantity.amount);
+        return new Quantity(result, this.unitOfMeasurement);
     }
 
     /**
@@ -65,7 +89,10 @@ public Quantity multiply(Quantity quantity) throws Exception {
      * @return частное
      */
     public Quantity divide(Quantity quantity) throws Exception {
-        return null;
+        // No check because quantity.amount cannot be null
+        validateEqualUnitOfMeasurement(quantity);
+        BigDecimal result = this.amount.divide(quantity.amount);
+        return new Quantity(result, this.unitOfMeasurement);
     }
 
     /**
@@ -75,6 +102,42 @@ public Quantity divide(Quantity quantity) throws Exception {
      * @return равные части числа
      */
     public Quantity[] divide(int n) throws Exception {
-        return null;
+        if (n == 0) {
+            throw new IllegalArgumentException("Невозможно разделить на 0 частей");
+        }
+
+        BigDecimal[] splitted = NumberSample.split(this.amount, n);
+        Quantity[] quantityResult = new Quantity[n];
+        for (int i = 0; i < n; i++) {
+            quantityResult[i] = new Quantity(splitted[i], this.unitOfMeasurement);
+        }
+        return quantityResult;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof Quantity quantity)) return false;
+        return Objects.equals(amount, quantity.amount) && Objects.equals(unitOfMeasurement, quantity.unitOfMeasurement);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(amount, unitOfMeasurement);
+    }
+
+    @Override
+    public String toString() {
+        return "Quantity{" +
+                "amount=" + amount +
+                ", unitOfMeasurement='" + unitOfMeasurement + '\'' +
+                '}';
+    }
+
+    private void validateEqualUnitOfMeasurement(Quantity qRight) {
+        if (!this.unitOfMeasurement.equals(qRight.unitOfMeasurement)) {
+            throw  new IllegalArgumentException("Единицы измерения не совпадают: "
+                    + this.unitOfMeasurement + " " + qRight.unitOfMeasurement);
+        }
     }
 }