title: Prompt box, ask value, store in cell. Add button for adapt
body: <p>I'm new to the world of google sheets. I was able to program very simple routines in Excel. Sorry if I couldn't find the answer anywhere on this site.</p>
  
  <p>My question is simple, has 2 parts:</p>
  
  <ol>
  <li>I would like to prompt a question box on opening the google sheet, asking a numeric value, after answering this, storing the numeric value to a specific cell, e.g. B3.</li>
  <li>I would like to have a button on multiple pages of the sheet, prompting the same question box to edit the value.</li>
  </ol>
  
  <p>Background:  </p>
  
  <p>I'm a medical doctor, I've created a sheet with many medications for small children in emergency situations. I would like a ask the user the age (and maybe later the weight, it's now calculated) of the child, so the age and weight are correct on all pages and the user is not in a hurry to find the right cell. If the user would like to edit the age, he uses the button, available on all sheets.</p>