וַיִּתֵּ֥ן דָּוִ֛יד לְאָרְנָ֖ן בַּמָּק֑וֹם שִׁקְלֵ֣י זָהָ֔ב מִשְׁקָ֖ל שֵׁ֥שׁ מֵאֽוֹת׃
So David gave to Ornan for the place six hundred shekels of gold by weight.
Read kabbalistic (mystical) interpretation of I Chronicles 21:25: and classical mystical sources.