64-bit lookahead carry unit adder based on four 16-bit LCU adders.
<a href="//commons.wikimedia.org/wiki/User:%D0%94.%D0%98%D0%BB%D1%8C%D0%B8%D0%BD" title="User:Д.Ильин">Д.Ильин</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>, translation, based on: <a href="//commons.wikimedia.org/wiki/File:64-bit_lookahead_carry_unit.svg" title="File:64-bit lookahead carry unit.svg">File:64-bit lookahead carry unit.svg</a> by <a href="https://en.wikipedia.org/wiki/User:Cburnett" class="extiw" title="en:User:Cburnett">Cburnett</a>