adding 3 numbers
Magic square - Wikipedia
In recreational mathematics, a square array of numbers, usually positive integers, is called a magic square if the sums of the numbers in each row, each column, ... When all the rows and columns but not both diagonals sum to the magic ...
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Addition with Larger Numbers
The pattern used to do addition is the same no matter how many digits are in the numbers or how many numbers you are adding together. Steps for Addition.
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Mathematics Grade 2 Units - NJ.gov
Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is ...
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