编写一个计算器，可以执行加、减、乘、除操作，并能处理小数和科学计数法。


{"operation": "multiply", "numbers":[2.2, 1e-3, -0.5]}
```python
import json

def calculator(operation, numbers):
    result = None
    
    if operation == "add":
        result = sum(numbers)
    elif operation == "subtract":
        result = numbers[0] - sum(numbers[1:])
    elif operation == "multiply":
        result = 1
        for num in numbers:
            result *= num
    elif operation == "divide":
        result = numbers[0]
        for num in numbers[1:]:
            result /= num
            
    return result

input_str = '{"operation": "multiply", "numbers":[2.2, 1e-3, -0.5]}'
input_dict = json.loads(input_str)
operation = input_dict['operation']
numbers = input_dict['numbers']
output = calculator(operation, numbers)
print(output)
```

输出结果为：`-0.0011`