How to read big number with Different units in Chinese

Mandarin/Chinese number has two units that English doesn't have (or at least, it has unique words for these units whilst English describes them with combinations of other units. These are:

万 - ten thousand
亿 - hundred million

万 comes up the most often and is the largest stumbling block for most people learning Mandarin numbers. In English, numbers are usually broken up into chunks of three digits. Because of 万, it's easier to break numbers up into groups of four in Mandarin. For example:

12000
Would be split into 12,000 in English (chunks of three digits), and the English reading "twelve thousand" would become more obvious. Split it the Chinese way, "1,2000," and the Chinese reading "一万两千" (one wan and two "thousand") becomes more logical.
More examples: