## Exponents

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### Exponents

Is it possible to calculate using exponents in Smartbuilder?
GeneS

Posts: 23
Joined: Fri May 08, 2009 11:19 am

### Re: Exponents

Hi Gene,
What a great question! No, SmartBuilder isn't built to handle exponents... but that doesn't mean you can't do it! Here's how - http://screencast.com/t/3YZm7ZnFZHtC

What fun!

I also made you an owner of the test lesson from the video if you want to poke around in it. If anyone else wants access to the test lesson, please respond here.

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Nav

Posts: 866
Joined: Mon Nov 05, 2007 2:58 pm

### Re: Exponents

Thanks for the replay and the screencast. I figured there was a workaround.
The exponent calculation will actually be done behind the scenes as part of a larger activity: a 'visual' future value calculator. Learners will use two groups of radio buttons to select an interest rate (1-10) and number of compounding periods (1-20), and we'll display the result both numerically and using the percent tracker. The results will change each time they click a different interest rate or number of periods.

Thanks.
GeneS

Posts: 23
Joined: Fri May 08, 2009 11:19 am

### Re: Exponents

I finished building my calculator using your exponent workaround. My base number will always include a decimal (for example, 1.04, 1.09, etc.) The mechanics of the calculator are working properly, but the calculations are slightly off. The problem has something to do with the decimals, because when I use whole numbers in the base, it works fine. My only guess is a rounding error is causing the problem. For example, 1.04 to the 9th power is 1.4233. My SB calculator shows it as 1.41. Is there a way to adjust how many decimal places Smartbuilder will read and display? Four decimal places would be ideal.

If you'd like to see what I mean, check out exponent test--Gene. The first page has the calculator that uses base number decimals and is a little off. Page 2 has whole numbers in the base and is accurate.
Thanks.
GeneS

Posts: 23
Joined: Fri May 08, 2009 11:19 am

### Re: Exponents

Hi Gene,
Hmm, Decimals... We are looking into adding more decimal places, but it might be a little while because of the underlying structure of SmartBuilder.

Currently there is only a partial workaround to this. You can multiply the 1.04 by one thousand and then divide the end result by 10^9 (the 9 because it was raised to the 9th power). It will still be rounded at the end to 1.42, but at least the intermediate calculations will be accurate.

Edit: Actually my math is off by several factors... You would have to divide by 10^27. so 10 ^ (9 * 3). The 9 is because you raised the value to the 9th power, the 3 because when you multiply it by 1000. You also don't have to use 1000, you could use 100, and you would divide at the end by 10^18. Hope that helps!

1.04^9 = 1.423311812421484544
104^9 = 1423311812421484544
1040^9 = 1423311812421484544000000000

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