Solution: Align the two addend units, and then add the numbers in the same counting unit respectively. When the addition result exceeds 10, it will reach the high position of 1, and the addition of the high position needs to accumulate the low position result of 1.

Problem solving process:

Step 1: 1+2=3

Step 2: 8+6=4 to the high position, 1.

Step 3: 7+0+ 1=8.

According to the above calculation steps, the comprehensive calculation result is 843.

Checking calculation: 843-62=78 1

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