それは１００ドル札だった。

that (indicating an item or person near the listener, the action of the listener, or something on their mind); it; that time; then; there (indicating a place near the listener); you

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

one; best; first; foremost; beginning; start; bottom string (on a shamisen, etc.)

circle (sometimes used for zero); 'correct' (when marking); symbol used as a placeholder (either because a number of other words could be used in that position, or because of censorship); period; full stop; maru mark; semivoiced sound; p-sound

dollar bill

be; is; indicates past or completed action; indicates light imperative