Final answer:
The product of all natural numbers from 1 to 81 ends with the digit 0 due to a pattern observed by examining the last digits of each number.
Step-by-step explanation:
The product of all natural numbers from 1 to 81 is a very large number. However, we can determine the last digit of the product without calculating the entire product.
If we look at the last digit of each number from 1 to 81, we can see a pattern:
- 1, 2, 3, 4, 5, 6, 7, 8, and 9 all end in different digits.
- 10, 20, 30, 40, 50, 60, 70, and 80 all end in 0.
- 11, 21, 31, 41, 51, 61, 71, and 81 all end in 1.
- 12, 22, 32, 42, 52, 62, and 72 all end in 2.
- ...
- 19 and 79 both end in 9.
The pattern repeats every 10 numbers. Since 81 is greater than 80 and divisible by 10, the last digit of the product will be the same as the last digit of 80, which is 0.
Therefore, the answer is A) 0.