Disk Block Address = 32-bit = 4B
Disk Block Size = 1KB
#of Disk Block Pointer that can fit in one block pointer = 1024/4 = 256
Direct pointer maximum file size = 8 * 1KB = 8KB
Due to Single Indirect Pointer maximum file size = 256 * 1KB = 256KB
Due to Double Indirect Pointer maximum file size = 256 * 256 * 1KB
Due to Triple Indirect Pointer maximum file size = 256 * 256 * 256 * 1KB
so, total file size (approx) = 2^34 Bytes.