### Instruction: What is the units digit of the sum $1! + 2! + 3! + 4! + 5! + \cdots + 1000!$? Let's program in Python in the response.### Response: # For numbers greater than 4, the units digit of factorial is always 0.
# So, we only need to calculate the units digit of the sum of 1! to 4!.

factorial = [1, 2, 6, 24]  # 1!, 2!, 3!, 4!
units_digit = sum(factorial) % 10  # Get the units digit
print(units_digit)