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Question
Circle the correct subtraction fact (by using casting out nine).
2362 – 632 = 1720
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Solution 1
2362 – 632 = 1720
2362 – 632 = 1720
2 – 5 = 10
2 = 10 + 5
2 = 1 + 5
2 = 5
2 = 2
Solution 2
Step 1: Calculate the digit sums (casting out nines)
Add the digits:
For 2362: 2 + 3 + 6 + 2 = 13 and 1 + 3 = 4 (digit sum)
For 632: 6 + 3 + 2 = 11 and 1 + 1 = 2 (digit sum)
For 1720: 1 + 7 + 2 + 0 = 10 and 1 + 0 = 1 (digit sum)
Step 2: Subtract the digit sums
4 − 2 = 2
Step 3: Compare with the digit sum of 1720
The digit sum of 1720 is 1, which does not match the expected digit sum (2).
he subtraction fact 2362 − 632 = 1720 is incorrect based on casting out nines.
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