Float to int casting in C# script with modulo giving division by zero error

I'm following this tutorial on using offsetting to animate a sprite sheet, which was going fine until I had to add controls for fps. The lesson is in JS, but I need to learn in C#. Unlike the example in the video, I have to explicitly cast the (Time.time * fps) from float to int, but no matter which method I try, it throws up a division by zero error on the line with the modulo. This makes little sense since print(frameNumber) shows nothing but integers. Does anyone know what's going on? I've been searching and searching, but can't find any answers

This is my code:

 public int columns;                // frames along x
 public int rows;                // y
 public int fps = 8;                // frames per sec
     
     void Update () 
     {
         int frameNumber = Time.time * fps; // Need to cast float to int here, but it causes error                    
             
         print (frameNumber);
         frameNumber = frameNumber % (columns * rows);                // ex. 1 % 16 = 1, 17 % 16 = 1. dividend = quotient * divisor + remainder, 1 = 0 * 16 + 1, 17 = 1 * 16 + 1.
         Vector2 size = new Vector2 (1.0f / columns, 1.0f / rows);     // ex. sheet has 16 frames across, scale texture to 1/16 width
         Vector2 offset = new Vector2 (frameNumber * size.x, rows);    // ex. (1 * 1/16, 1)
         
         renderer.material.mainTextureOffset = offset;                // offsets texture to other "frames"
         renderer.material.mainTextureScale = size;                    // scale texture to proper size