How to get partition size from MBR record?

Question

linux

I understand 80 00 00 0c, but I don’t understand how to get 400mb from it.

Here is its markup

Answer 1

Let's write not in words, but in bytes:
00000000: 00 20 21 00 83 1e 2b 33 00 08 00 00 00 80 0c 00
0x00: 00 - non-boot partition
0x01: 20 21 00 - CHS of the first sector: head 32, sector 33, cylinder 0
0x04: 83 - partition type: Linux 0x05 :
1e 2b 33 - last sector CHS: head 30, sector 43, cylinder 51 = 819200 Multiply the last value by 512 (sector size) 819200 * 512 = 419430400 = 409600 KiB = 400 MiB