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Everyday MathematicsPartial-Sums Addition

Partial-Sums AdditionPartial-sums addition involves:Understanding place value;Finding partial sums; andAdding partial sums to get the final answer.

Everyday Mathematics

Partial-Sums AdditionSolve: 634 + 918We begin by thinking of the expanded notation for the numbers being added.634 = 600 + 30 + 4918 = 900 + 10 + 8With partial-sums addition, we can start from the right orthe left. Children often prefer to start from the greatest place-value position.

Everyday Mathematics

Partial-Sums AdditionFirst we add the hundreds.634+ 918600 + 900 =1,500The numbers written in blue show our thinking and thenumbers written in black show what we write to solve the problem.Everyday Mathematics

Partial-Sums AdditionNext we add the tens.634+ 918600 + 900 =1,50030 + 10 =40

Everyday Mathematics

Partial-Sums AdditionThen we add the ones.634+ 918600 + 900 =1,50030 + 10 =404 + 8 =12Everyday Mathematics

Partial-Sums AdditionFinally, we add the partial sums to findthe answer.634+ 918 1,500634 + 918 = 1,552

40+ 121,552Everyday Mathematics634+918=1552

Partial-Sums AdditionEveryday Mathematics

When children use partial-sums addition, they practice skillsrelated to number sense and algebraic reasoning. For example: Understanding and using place value; Thinking about numbers in expanded notation; and Using addition fact extensions such as 600 + 900 = 1,500.If children work from left to right, which is generally theirinclination, they begin the problem-solving process with areasonable estimate of what the final answer should be.