To find Confidence Intervals of Proportions using Statistics Made Easy at https://www.tinspireapps.com/?a=SPME use option 7

Next, the given proportion po , sample size n and the confidence level alpha as shown below:

Automatically, the correct setup and solution shows in the bottom window.

To also find the sample size given the Margin of Error use option 9:

you will enter the given Margin of Error, proportion and the confidence level Alpha

Again, the correct setup is shown and the sample size is computed step by step, here we get n>=441.7187