The following formula is used to calculate the specific gravity of a material. SG = Ï / ÏW. 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.
Donât throw bank statements away after six years. August 12, 2013 85237 ViewsFacebook: 808Twitter: 41. The conventional wisdom is you only need to keep bank, credit card and other personal finance documents for six years. This is because HMRC (the taxman) can only ask you to go back that far if youâre being investigated for tax purposes.
Bank records. Length of time to keep, and why: From one year to permanently. 1  Go through your checks each year and keep those related to your taxes, business expenses, home improvements and mortgage payments. 2  Shred those that have no long-term importance.ength of time to keep, and why: From six years to permanently. 1  Keep all records documenting the purchase price and the cost of all permanent improvements -- such as remodeling, additions and installations.