# Inaccurate Decimal multiplication and division results

XMLWordPrintableJSON

#### Details

• Bug
• Status: Resolved
• Blocker
• Resolution: Fixed
• 3.2.4, 3.3.3, 3.4.1, 3.5.0, 4.0.0

#### Description

Decimal multiplication and division results may be inaccurate due to rounding issues.

## Multiplication:

```scala> sql("select  -14120025096157587712113961295153.858047 * -0.4652").show(truncate=false)
+----------------------------------------------------+
|(-14120025096157587712113961295153.858047 * -0.4652)|
+----------------------------------------------------+
|6568635674732509803675414794505.574764              |
+----------------------------------------------------+
```

6568635674732509803675414794505.574763

Please note that the last digit is 3 instead of 4 as

```scala> java.math.BigDecimal("-14120025096157587712113961295153.858047").multiply(java.math.BigDecimal("-0.4652"))
val res21: java.math.BigDecimal = 6568635674732509803675414794505.5747634644
```

Since the factional part .574763 is followed by 4644, it should not be rounded up.

## Division:

```scala> sql("select -0.172787979 / 533704665545018957788294905796.5").show(truncate=false)
+-------------------------------------------------+
|(-0.172787979 / 533704665545018957788294905796.5)|
+-------------------------------------------------+
|-3.237521E-31                                    |
+-------------------------------------------------+
```

-3.237520E-31

Please note that the last digit is 0 instead of 1 as

```scala> java.math.BigDecimal("-0.172787979").divide(java.math.BigDecimal("533704665545018957788294905796.5"), 100, java.math.RoundingMode.DOWN)
val res22: java.math.BigDecimal = -3.237520489418037889998826491401059986665344697406144511563561222578738E-31
```

Since the factional part .237520 is followed by 4894..., it should not be rounded up.

#### People

Kazuyuki Tanimura
Kazuyuki Tanimura