Tag Archives: Prime Factorization

SAT/ACT problem of the week, October 06, 2016

An integer x has n zeros at the end if and only if it is divisible by 10^n . For example, 12,500,000 is divisible by 10^5 but not by 10^6 .

How many zeros are at the end of 1 \times 2 \times 3 \times \cdots \times 100?

  1. 1 (check answer)
  2. 3 (check answer)
  3. 10 (check answer)
  4. 20 (check answer)
  5. 24 (check answer)

Solutions, hints, and questions are welcomed. A full solution will be posted on October 12th. If you would like to learn how to enter math formulas into this blog, visit the WordPress LaTeX tutorial page.

SAT problem of the week, October 06, 2014

An integer x has n zeros at the end if and only if it is divisible by 10^n . For example, 12,500,000 is divisible by 10^5 but not by 10^6 .

How many zeros are at the end of 1 \times 2 \times 3 \times \cdots \times 100?

  1. 1 (check answer)
  2. 3 (check answer)
  3. 10 (check answer)
  4. 20 (check answer)
  5. 24 (check answer)

Solutions, hints, and questions are welcomed. A full solution will be posted on October 12th. If you would like to learn how to enter math formulas into this blog, visit the WordPress LaTeX tutorial page.