1.2 Useful Estimates 10 almost automatically.For estimating such expressions from below,which is usually more delicate,we can often use 1-p≥ep, which is valid for0≤p≤1.2 Useful Estimates 10 almost automatically. For estimating such expressions from below, which is usually more delicate, we can often use 1 − p ≥ e −2p , which is valid for 0 ≤ p ≤ 1 2