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: 420+500
    Solution:
    420+500 = 920
    Column vertical calculation:

			4	2	0
➕			5	0	0
			9	2	0

[2/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 220+400
    Solution:
    220+400 = 620
    Column vertical calculation:

			2	2	0
➕			4	0	0
			6	2	0

[3/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 320+400
    Solution:
    320+400 = 720
    Column vertical calculation:

			3	2	0
➕			4	0	0
			7	2	0

[4/7 Integer column vertical calculation]
    Question type: Integer subtraction
    Original question: 820-500
    Solution:
    820-500 = 320
    Column vertical calculation:

			8	2	0
➖			5	0	0
			3	2	0

[5/7 Integer column vertical calculation]
    Question type: Integer subtraction
    Original question: 720-400
    Solution:
    720-400 = 320
    Column vertical calculation:

			7	2	0
➖			4	0	0
			3	2	0

[6/7 Integer column vertical calculation]
    Question type: Integer subtraction
    Original question: 720-300
    Solution:
    720-300 = 420
    Column vertical calculation:

			7	2	0
➖			3	0	0
			4	2	0

[7/7 Integer column vertical calculation]
    Question type: Integer addition
    Original question: 140+300
    Solution:
    140+300 = 440
    Column vertical calculation:

			1	4	0
➕			3	0	0
			4	4	0

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>>注：本次最多计算 7 道题。

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