搜尋find the difference. 6x3 + 18x2 - 3x2 =

搜尋find the difference. 6x3 + 18x2 - 3x2 =

Count and calculate using this fully customizable abacus. Features:* 5 to 8 Counting Rows* 4 Bead Types* 4 Frame Types* 2 Modes (Standard and Chinese) …
Abacus