額
がく · gaku · JLPT N3 · noun
sum
🖼️💴 頁 head + 客 guest: first a forehead, then a framed plaque, then a sum
額 first meant forehead, which is why it has 頁 (head). A plaque hung high over a door was the building's forehead, so it came to mean frame (額縁, gakubuchi). The figure written on a ledger or plaque became an amount: 金額 (kingaku), a sum of money.
ひたい · hitai · JLPT N3 · noun
brow
🤦 hitai ≈ hit-eye: the brow is the spot just above the eye you hit
額 = 頁 (head) + 客 (a sound hint, gaku). The 頁 part tells you it belongs to the head. A facepalm hits the hitai, the forehead. In Sino-Japanese words 額 is read gaku and means amount or a picture frame, as in 金額 (kingaku, sum of money).