South African Class 15B 4-8-2 September 1997. South African Class 15B 4-8-2 The South African Railways Class 15B 4-8-2 of 1918 was a steam locomotive. Between 1918 and 1922, the South African Railways placed thirty Class 15B steam locomotives with a 4-8-2 Mountain type wheel arrangement in service. The Class 15B was ordered at a time when further orders of the earlier Class 15 models were unobtainable from manufacturers in the United Kingdom as a result of wartime disruption in Europe. The first batch of ten Class 15B 4-8-2 steam locomotives for the South African Railways (SAR) was therefore ordered from the Montreal Locomotive Works
1/2 + 1/4 + 1/8 + 1/16 + ⋯ 1/2 + 1/4 + 1/8 + 1/16 + ⋯ In mathematics, the infinite series is an elementary example of a geometric series that converges absolutely. There are many different expressions that can be shown to be equivalent to the problem, such as the form: 2 + 2 + 2 + ... The sum of this series can be denoted in summation notation as: As with any infinite series, the infinite sum is defined to mean the limit of the sum of the first terms as approaches infinity. Multiplying by 2 reveals a useful relationship: Subtracting from both sides, As approaches