Overview: 7 questions will be solved this time.Among them
           ☆7 integer calculations

[1/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 490+500
    Solution:
    490+500 = 990
    Column vertical calculation:

			4	9	0
➕			5	0	0
			9	9	0

[2/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 290+400
    Solution:
    290+400 = 690
    Column vertical calculation:

			2	9	0
➕			4	0	0
			6	9	0

[3/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 390+400
    Solution:
    390+400 = 790
    Column vertical calculation:

			3	9	0
➕			4	0	0
			7	9	0

[4/7 Integer column vertical calculation]
    Question type: Integer subtraction
    Original question: 890-500
    Solution:
    890-500 = 390
    Column vertical calculation:

			8	9	0
➖			5	0	0
			3	9	0

[5/7 Integer column vertical calculation]
    Question type: Integer subtraction
    Original question: 790-400
    Solution:
    790-400 = 390
    Column vertical calculation:

			7	9	0
➖			4	0	0
			3	9	0

[6/7 Integer column vertical calculation]
    Question type: Integer subtraction
    Original question: 790-300
    Solution:
    790-300 = 490
    Column vertical calculation:

			7	9	0
➖			3	0	0
			4	9	0

[7/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 210+300
    Solution:
    210+300 = 510
    Column vertical calculation:

			2	1	0
➕			3	0	0
			5	1	0

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>>注：本次最多计算 7 道题。

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