South African Class 15F 4-8-2 picture shows pre-war NBL-built no. 2940 "Lynette" with an ex Class 23 type EW tender, at speed near Princess station on the Johannesburg-Magaliesburg line on 6 April 1992. South African Class 15F 4-8-2 The South African Railways Class 15F 4-8-2 of 1938 was a steam locomotive. The Class 15F was the most numerous steam locomotive class in South African Railways service. Between 1938 and 1948, 255 of these locomotives with a 4-8-2 Mountain type wheel arrangement entered service. The Class 15F 4-8-2 Mountain type steam locomotive was designed by W.A.J. Day, Chief Mechanical Engineer (CME) of the South African Railways
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