In some country, a 6-character license plate is composed of capital letters (12 letters in total) and decimal

In some country, a 6-character license plate is composed of capital letters (12 letters in total) and decimal digits in any order. Each character is encoded with the same and minimum possible number of bits, and each number – with the same and minimum possible number of bytes. Determine the amount of memory required to store 32 license plates.

N (number of characters in the alphabet) = 12 letters + 10 numbers = 22
k = 6 characters
Since N = 2 ^ i, we assume that i = 5 bits, since 22 is closest to this power of two (16 <22 <32)!
That is, one character takes 5 bits, then one number takes (5 * 6) / 8 = 4 bytes (to get bytes, divide by 8)
I (memory size) = 32 * 4 = 128 bytes