The Math Forum

Ask Dr. Math - Questions and Answers from our Archives
Associated Topics || Dr. Math Home || Search Dr. Math

Multiply Two Numbers (No Zeros) to make 5 Billion

Date: 01/05/2002 at 10:45:06
From: Jessica
Subject: Very big problem.

Dr. Math,

I am doing a 7th grade scavenger hunt for math. I have done almost 
everything except one problem, which is as follows:

What two numbers - neither of them containing zeros - can be 
multiplied together to make 5,000,000,000?

I have tried everything, but I always come up with a zero in the 
answer. Please help me.

Date: 01/05/2002 at 17:09:00
From: Doctor Jaffee
Subject: Re: Very big problem.

Hi Jessica,

Here's a suggestion. Factor your number completely. When you are 
finished, you will have nothing but 2's and 5's. Multiply all of the 
2's together, then multiply all of the 5's together. You now have two 
numbers that satisfy the requirements of the problem.

Give it a try and if you want to check your solution with me, write 
back. If you are having difficulties, let me know and show me what you 
have done so far, and I'll try to help you some more.

Good luck.

- Doctor Jaffee, The Math Forum   
Associated Topics:
High School Puzzles
Middle School Puzzles

Search the Dr. Math Library:

Find items containing (put spaces between keywords):
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search

Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.