# Number Sense Blog

By Mathnasium | Added Mar 28, 2018

If you had a time machine, when in history--or into the future--would you go?

It’s fun to think about what we might do with time travel, but even more fun to think about HOW we might time travel, because the how of this fantastical adventure would inevitably require scientific and mathematical thinking. Even when that scientific thinking is more science-fiction than science-fact, the math will always be firmly rooted in reality. So get ready to practice your elementary math skills, including multiplication, division, and rounding, as we figure out how we might travel through time in this week’s fun word problem challenge!

Challenge: A time machine requires 1.21 gigawatts of electricity to travel through time. A car battery generates about 12,000 watts to start a car. How many car batteries would be needed to send the time machine through time?

(Hint: A gigawatt is a billion watts.)

When you're ready look below to check your solution against ours.

Solution: 1.21 gigawatts is equal to 1.21 × 1,000,000,000 = 1,210,000,000 watts. Dividing 1,210,000,000 by 12,000 is tricky, but we can divide both numbers by 1,000 first to make the problem easier: 1,210,000 ÷ 12 = 100,8331/3. Since batteries aren’t sold in thirds, we round up. The time machine would need 100,834 car batteries to travel through time.

(Image above from Back To The Future, courtesy of Amblin Entertainment Universal Pictures.)

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Numberphile: http://www.numberphile.com/

PTO Today: http://www.ptotoday.com/

STEM Connector: http://blog.stemconnector.org/

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