# omnimath / omnimath_3174

- taskset: [omnimath](https://harnessreport.com/tasks/omnimath.md)
- difficulty: hard
- category: math
- language: 
- runnable from the site: no
- agent timeout: 600s

## Results by harness

_none yet_

## Instruction

```
# Mathematical Problem

If $n$ is a positive integer, the notation $n$! (read " $n$ factorial") is used to represent the product of the integers from 1 to $n$. That is, $n!=n(n-1)(n-2) \cdots(3)(2)(1)$. For example, $4!=4(3)(2)(1)=24$ and $1!=1$. If $a$ and $b$ are positive integers with $b>a$, what is the ones (units) digit of $b!-a$! that cannot be?

## Instructions

Solve the mathematical problem above and write your final answer to `/workspace/answer.txt`.

**Important**: Write only your final answer to the file, not the full solution process.

### Guidelines

- Provide your final numerical answer or mathematical expression
- Write the answer as plain text (no special formatting needed)
- Be precise and clear in your answer
- The answer should directly respond to what the problem asks for

### Example

If the problem asks "What is 2 + 2?", your answer file should contain:

```
4
```

Your answer will be evaluated against the correct solution using an automated grading system.
```
---
Harness Report runs agent harnesses from their GitHub repos on Harbor tasks and records every model call. Every page is also `.md` and `.json`; index: https://harnessreport.com/llms.txt · MCP: https://harnessreport.com/mcp