Intel processor instructions for arithmetic operations expect integers to be represented in a particular way in memory.

The int type typically is expected to be represented by a sequence of 32 1's and 0's; that is, 32 bits.

Representation of integers using only 1's and 0's means that the (decimal) value of each position is a power of 2: 1, 2, 4, 8, 16, etc. instead of 1, 10, 100, 1000, etc.

Binary:            1   0  1  1 = 1 * 8    + 0 * 4   + 1 * 2  + 1 * 1 = 11 (in decimal)
Position value:    8   4  2  1

Decimal:           1   0  1  1 = 1 * 1000 + 0 * 100 + 1 * 10 + 1 * 1 = 1011 (in decimal)
Position value: 1000 100 10  1
   

With 4 bits, there are 16 (= 2 x 2 x 2 x 2) possible combinations of 0's and 1's in each of the 4 positions.