B5 paper size (182 mm x 257 mm)
Standard paper size used in notebooks, textbooks, and printing.
This notebook is B5 size.
Ｂ５判の用紙に印刷してください。
Please print on B5 size paper.
Standard notation for B5 size paper.
Kanji numeral variant; less common than the Arabic numeral form.
From the B-series paper size standard (ISO 216) combined with 判 (はん, 'size').