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androidcountapp-inventor

Count until zero

I am beginner and trying to write some calculations with App Inventor 2.

I am trying to write a code to calculate Net present value. The formula of NPV = - investment + CF/(1+i)power up by years of investment, which means if years of investment are > 1 the second part of formula will repeat until it reached the number of years.

I successfully code the formula for one year that works correct, but have problem with the "repeating" the second part powered by number of years.

I tried to declare years as variable to use it as powering number but think something is wrong with it.

In my opinion I need to split the powering number somewhere to memory and then increase it by 1 until the required number. However have no clue how to do it.

Can anyone help?

Screenshot of the blocks

enter image description here

Solution

  • Following the calculation from the NPB Calculator, enter image description here

    this is converted into blocks the following enter image description here

    Note: for a better clarity and to avoid such long calculation blocks as in your screenshot, I used External Inputs instead of Inline Inputs, which is the default. You can switch that from the context menu after doing a right mouse click onto one of the calculation blocks.

    EDIT: screenshot updated for changing cashflows using a list.
    See also How to work with Lists by Saj and
    How to work with Lists and Lists of lists (pdf) by appinventor.org