standard form      
noun [ U ]  mathematics specialized uk/ˈstæn.dəd ˌfɔːm/ us/ˈstæn.dɚd ˌfɔːrm/ (also standard index form)
 (书写非常大的数字时的)标准形式
a way of writing a very large number with one number before the decimal point, multiplied by a power of 10. For example, 280,000 is 2.8 × 105