Mathematical
The wooden box without cover is equipped with PVC number cards 1-9000, thousands of bits 16.5*5.5, hundreds of bits 12.5*5.5, tens of bits 9*5.5, and units bits 4*5.5
The wooden box without cover is equipped with PVC number cards 1-9000, thousands of bits 16.5*5.5, hundreds of bits 12.5*5.5, tens of bits 9*5.5, and units bits 4*5.5