Where it comes from
The line in the source
ポケットモンスター ブラック・ホワイト（昨年9月発売）の販売本数：470万本超 In English
Black/White (released last September) sold over 4.7m (fetch paraphrase).
Explore / Figure
Record
Black white japan units cumulative, to Jan 2011
4.7 millions of units To Jan 2011
EstimateOur model or estimate. Treat it as an order of magnitude.
Found in one pass only. The research team reads every source twice, independently; this record turned up in one reading but not the other, so treat it as less certain than its grade.