( 1) 19-7=9
The left 9 is removed and becomes 5, and the right 9 adds up to 8.
15-7=8
(2) 19-329 15
The 3 on the left moves one and becomes 5.
19-5=9+5
What courses do advanced mathematics refer to?
High number is a unified name, and its scope varies according to different majors.
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