2-8-8-4 wheels. The locomotive's superstructure was attached to the rear group, while the forward group and leading truck could swing laterally on curves. All Yellowstones had fairly small drivers of . (For greater speeds, the Union Pacific Railroad chose a four-wheel leading truck and drivers of for its Big Boy 4-8-8-4 class.) Several classes of Yellowstone, especially the Duluth, Missabe and Iron Range's locomotives, are among the largest steam locomotives, with the exact ranking depending on the criteria used. The Northern Pacific Railway was the first railroad to order a 2-8-8-4. The first was built in 1928 by American Locomotive Company;
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