Step-by-step explanation:
See below for a complete "100 square". Locate your given numbers on the square and fill in the corresponding blanks.
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Each number left or right of a given number is 1 less or 1 more (respectively). Each number above or below a given number is 10 less or 10 more (respectively). Adding or subtracting 1 or 10 are supposed to be simple operations.
It can work well to start with empty boxes that are adjacent to given numbers.
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From top to bottom, the missing numbers in the upper left excerpt are ...
2, 12, 22, 32
From left to right, the missing numbers in the top row of the second excerpt are ...
16, 17, 18, 19, 20
and so it goes ...