diff --git a/uncloud/uncloud_pay/models.py b/uncloud/uncloud_pay/models.py
index 24cc858..4e5770a 100644
--- a/uncloud/uncloud_pay/models.py
+++ b/uncloud/uncloud_pay/models.py
@@ -8,6 +8,7 @@ from math import ceil
 from datetime import timedelta
 from calendar import monthrange
 
+from decimal import Decimal
 import uuid
 
 # Define DecimalField properties, used to represent amounts of money.
@@ -113,7 +114,7 @@ class Bill(models.Model):
 
     @property
     def total(self):
-        return reduce(lambda acc, record: acc + record.amount(), self.records, 0)
+        return reduce(lambda acc, record: acc + record.amount, self.records, 0)
 
     @property
     def final(self):
@@ -133,7 +134,8 @@ class BillRecord():
         self.recurring_period = order_record.recurring_period
         self.description = order_record.description
 
-    def amount(self):
+    @property
+    def recurring_count(self):
         # Compute billing delta.
         billed_until = self.bill.ending_date
         if self.order.ending_date != None and self.order.ending_date < self.order.ending_date:
@@ -166,21 +168,23 @@ class BillRecord():
             (_, days_in_month) = monthrange(
                     self.bill.starting_date.year,
                     self.bill.starting_date.month)
-            adjusted_recurring_price = self.recurring_price / days_in_month
-            amount = adjusted_recurring_price * days
+            return Decimal(days / days_in_month)
         elif self.recurring_period == RecurringPeriod.PER_DAY:
             days = ceil(billed_delta / timedelta(days=1))
-            amount = self.recurring_price * days
+            return Decimal(days)
         elif self.recurring_period == RecurringPeriod.PER_HOUR:
             hours = ceil(billed_delta / timedelta(hours=1))
-            amount = self.recurring_price * hours
+            return Decimal(hours)
         elif self.recurring_period == RecurringPeriod.PER_SECOND:
             seconds = ceil(billed_delta / timedelta(seconds=1))
-            amount = self.recurring_price * seconds
+            return Decimal(seconds)
         else:
             raise Exception('Unsupported recurring period: {}.'.
                     format(record.recurring_period))
 
+    @property
+    def amount(self):
+        amount = self.recurring_count * self.recurring_price
         if self.order.starting_date > self.bill.starting_date:
             amount += self.setup_fee
 
diff --git a/uncloud/uncloud_pay/serializers.py b/uncloud/uncloud_pay/serializers.py
index fcbaf73..051b882 100644
--- a/uncloud/uncloud_pay/serializers.py
+++ b/uncloud/uncloud_pay/serializers.py
@@ -96,6 +96,7 @@ class BillRecordSerializer(serializers.Serializer):
     description = serializers.CharField()
     recurring_period = serializers.CharField()
     recurring_price = serializers.DecimalField(max_digits=10, decimal_places=2)
+    recurring_count = serializers.DecimalField(max_digits=10, decimal_places=2)
     setup_fee = serializers.DecimalField(max_digits=10, decimal_places=2)
     amount = serializers.DecimalField(max_digits=10, decimal_places=2)