ClickHouse/docs/en/sql-reference/aggregate-functions/reference/sumkahan.md
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---
slug: /en/sql-reference/aggregate-functions/reference/sumkahan
sidebar_position: 145
title: sumKahan
---
Calculates the sum of the numbers with [Kahan compensated summation algorithm](https://en.wikipedia.org/wiki/Kahan_summation_algorithm)
Slower than [sum](./sum.md) function.
The compensation works only for [Float](../../../sql-reference/data-types/float.md) types.
**Syntax**
``` sql
sumKahan(x)
```
**Arguments**
- `x` — Input value, must be [Integer](../../../sql-reference/data-types/int-uint.md), [Float](../../../sql-reference/data-types/float.md), or [Decimal](../../../sql-reference/data-types/decimal.md).
**Returned value**
- the sum of numbers, with type [Integer](../../../sql-reference/data-types/int-uint.md), [Float](../../../sql-reference/data-types/float.md), or [Decimal](../../../sql-reference/data-types/decimal.md) depends on type of input arguments
**Example**
Query:
``` sql
SELECT sum(0.1), sumKahan(0.1) FROM numbers(10);
```
Result:
``` text
┌───────────sum(0.1)─┬─sumKahan(0.1)─┐
│ 0.9999999999999999 │ 1 │
└────────────────────┴───────────────┘
```