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

[1/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 21×40
    Solution:
    21×40 = 840
    Column vertical calculation:

							2	1
✖							4	0
							0	0
						8	4
						8	4	0

[2/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 74×20
    Solution:
    74×20 = 1480
    Column vertical calculation:

							7	4
✖							2	0
							0	0
					1	4	8
					1	4	8	0

[3/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 52×20
    Solution:
    52×20 = 1040
    Column vertical calculation:

							5	2
✖							2	0
							0	0
					1	0	4
					1	0	4	0

[4/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 25×30
    Solution:
    25×30 = 750
    Column vertical calculation:

							2	5
✖							3	0
							0	0
						7	5
						7	5	0

[5/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 14×30
    Solution:
    14×30 = 420
    Column vertical calculation:

							1	4
✖							3	0
							0	0
						4	2
						4	2	0

[6/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 18×20
    Solution:
    18×20 = 360
    Column vertical calculation:

							1	8
✖							2	0
							0	0
						3	6
						3	6	0

[7/7 Integer column vertical calculation]
    Question type: Integer multiplication
    Original question: 13×30
    Solution:
    13×30 = 390
    Column vertical calculation:

							1	3
✖							3	0
							0	0
						3	9
						3	9	0

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>>注：本次最多计算 7 道题。

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