The formal banking numeral for 一 (one), used on cheques, contracts and receipts. Its many strokes make it nearly impossible to forge by adding a line, unlike the single stroke of 一.
The top piece sits like a lid over the vessel below. In the older form this whole character pictured a sealed 壶 (pot) standing for 'concentrated into one'.
The body is a 壶 (pot) with 吉 inside as the sound. A sealed single vessel gave the meaning 'one, single, undivided', later borrowed as the anti-fraud numeral.
