ABSTRACT
The Rule of 69, an approximation for determining the number of periods in which a sum will double at a given interest rate, was 'rediscovered' in 1974. This Rule has been known since at least 1900. On 14 March 1900, at a meeting of the Incorporated Accountants Students' Society of London, T. Tinner, who was a member of that society, presented a paper, Some Actuarial Calculations for Accountants. In the paper he derived the Rule of 69 for determining the number of periods required to depreciate an asset to one-half its original value without reference to tables. The paper was reprinted in the Lectures and Transactions of the Incorporated Accountants Students' Society of London for the Year 1900. These comments have a remarkably modern tone and this lesson can be learned from them: A greater attention to the historical development of accounting thought undoubtedly would have a beneficial influence on progress.
