For computers to be able to perform billions of operations per second, they need strategies to make calculations quickly. Carry-lookahead adders make addition much more efficient by reducing the amount of time circuits spend waiting for carries to be calculated. *** Spanning Tree is an educational video series about computer science and mathematics. See more at To be notified when a new video is released, sign up for the Spanning Tree mailing list at Spanning Tree is created by Brian Yu. Email me at brian@ to suggest a future topic. 0:00 Ripple Carry Adders 2:40 Carry-Lookahead 7:40 Combining CLAs