A 6-inch phone is too small for tables with 20 columns and 50 rows. An 8-inch or 10-inch tablet (e.g., Samsung Galaxy Tab or iPad) displays a full A4 page comfortably.
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For students in vocational training, cost is a significant factor. While they must often buy the physical book for class, having a backup PDF on a laptop allows for studying on the commute or during breaks without lugging the heavy textbook around. A 6-inch phone is too small for tables