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Add multiples of 100 mentally

Adding a multiple of 100 means combining whole hundreds: the hundreds place increases by the corresponding number of hundreds while the tens and ones remain unchanged. For three-digit numbers with results within 1,000, this reasoning supports efficient mental addition and can be represented by jumps of 100 on a number line or by place-value notation; it does not include larger numbers or generalized algorithms beyond this range.

Detailed Explanation: Add multiples of 100 mentally

To add a multiple of 100100, add whole hundreds. The tens and ones digits stay the same.

Example:

347+500347+500
  1. Think of 500500 as 55 hundreds.
  2. Start with 347347 and add 100100 five times:
347→447→547→647→747→847347\to447\to547\to647\to747\to847
  1. The hundreds digit increased by 55, while the 44 tens and 77 ones stayed the same.

Therefore,

347+500=847347+500=\boxed{847}

Learn by doing: Add multiples of 100 mentally

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Addition - Whole Number - Add Multiple of 100 to a Number


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