The following formula is used to calculate the specific gravity of a material. Where SG = specific gravity, Ï = density of the material (kg/m3), ÏW = density of water ( kg/m3). The reference density of water at 4oC (39oF) is used as the reference as these are the conditions of maximum density.
Most business owners donât know how long they should hold on to old records. According to the IRS, hereâs how long you should keep those records: Permanently: 1  general ledgers and journals. 2  payroll records, including W-2s, 940s, 941s. 3  year-end financial statements.4  tax returns and supporting documents. 5  articles of incorporation, bylaws, meeting minutes, etc. 6  retirement plan records.ost business owners donât know how long they should hold on to old records. According to the IRS, hereâs how long you should keep those records: Permanently: 1  general ledgers and journals. 2  payroll records, including W-2s, 940s, 941s. 3  year-end financial statements. 4  tax returns and supporting documents.
Keep monthly statements for one year; you can dump them if your annual statement summarizes all activity. Keep the yearly summaries as long as you own the security, plus seven years. You need proof of your purchases to prove capital gains and losses on your tax return.nce you've purged, separate must-keep papers into three categories: those you need to keep for one calendar year, those you need to keep for a longer period and hard-to-replace documents like birth and marriage certificates. (See chart: What records to keep, how long to keep them .) Then decide on a home for each.