Homework for Week 2

Using ideas we talked about in class this week, you should now be able to answer the following questions without doing a lot of multiplication. Bring your work to class, we will be collecting it.

1. Note that 25 times 4 is 100, which has two zeros on the end of it. Explain where the zeros come from (why is there more than one). Now how many zeros are there at the end of 25! (Remember 25! = 25 x 24 x 23 x ... x 1)?
2. Now you should be able to answer last week's question: if I multiply all the numbers from 1 to 100 together, how many zeros will be at the end of the answer?