In base 16, the numbers 10-15 are denoted by the letters a-f. So in the units place, we have
c₁₆ + e₁₆ = 12 + 14 = 16 + 10 = 1a₁₆
Carry the 1 to the next place value:
4₁₆ + c₁₆ + 1₁₆ = 4 + 12 + 1 = 16 + 1 = 11₁₆
Carry the 1:
d₁₆ + b₁₆ + 1₁₆ = 13 + 11 + 1 = 16 + 9 = 19₁₆
Carry the 1:
3₁₆ + 4₁₆ + 1₁₆ = 3 + 4 + 1 = 8₁₆
So, we end up with
3d4c₁₆ + 4bce₁₆ = 891a₁₆
