Bing found the following results
Calculate the sum of a list of numbers - Online Tools
Long Addition Calculator
Addition Calculator - Math.net
Addition - Math is Fun
Basic Addition | Arithmetic (video) | Khan Academy
Addition and Subtraction | Arithmetic | Khan Academy
Addition in Math: Definition, Examples, Formulas - DoodleLearning
Addition Calculator: Add Numbers & Learn to Calculate the Sum
Example: Adding 2-digit numbers (no carrying) - Khan Academy
Addition Calculator
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