I'll write out a count without a digit if it's immediately next to a value. Like without other qualifiers: "three 500 kVA transformers", versus "3 500 kVA transformers" (horrible), or even "three [3] 500 kVA transformers" (acceptable, but perhaps cluttered)
(Also note the space between value and unit—technically required but I'm not consistent about it)
I'll write out a count without a digit if it's immediately next to a value. Like without other qualifiers: "three 500 kVA transformers", versus "3 500 kVA transformers" (horrible), or even "three [3] 500 kVA transformers" (acceptable, but perhaps cluttered)
(Also note the space between value and unit—technically required but I'm not consistent about it)