Adding a multiple of 10 to a two-digit number is understood as increasing the tens value while keeping the ones value unchanged; for example, 47 + 30 is 7 ones and 7 tens, or 77. The reasoning relies on place value and composing or decomposing groups of ten, and applies to sums within 100 rather than to larger numbers, formal multi-digit algorithms, or generalized symbolic rules.
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Detailed Explanation: Add multiples of 10 mentally
When you add a multiple of 10, the ones digit stays the same. You only increase the number of tens.
Example: Find .
- Think of as tens and ones.
- is tens.
- Add the tens: tens tens tens.
- Keep the ones unchanged.
So, is tens and ones:
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Addition - Whole Number - Add Multiple of 10 to a Number - Column
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- Addition - Whole Number - Add Multiple of 10 to a Number - Column
- Addition - Whole Number - Add Multiple of 10 to a Number
- Addition - Whole Number - Add 10 to a Number
- Addition - Whole Number - Add Multiples of 10
- Addition - Whole Number - Add 10 to a Number - Column
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