```ts
export function tilesAcross(length: number, tile: number): number {
  return Math.ceil(length / tile);
}

export function tilesNeeded(width: number, height: number, tile: number, spare: number): number {
  const totalTiles = width * height;
  const breakageAllowance = (totalTiles * spare) / 100;
  const totalBreakages = Math.ceil(breakageAllowance / tile);
  return Math.ceil(totalTiles + totalBreakages);
}
```