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Everyday Mathematics Trade-First Subtraction

Everyday Mathematics Trade-First Subtraction. Trade-First Subtraction. As the name suggests, trade-first subtraction involves making all place-value trades first. This makes trade-first easier because we don’t have to switch back and forth between subtracting and trading.

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Everyday Mathematics Trade-First Subtraction

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  1. Everyday MathematicsTrade-First Subtraction

  2. Trade-First Subtraction As the name suggests, trade-first subtraction involves making all place-value trades first. This makes trade-first easier because we don’t have to switch back and forth between subtracting and trading. Everyday Mathematics

  3. Trade-First Subtraction • Solve: 471 – 293 • We set up the problem by • writing the numbers in their • place-value columns. • H = hundreds • T = tens • O = ones H 4 7 1 – 2 9 3 T O Everyday Mathematics

  4. Trade-First Subtraction Solve: 471 – 293 H T O 6 11 4 7 1 – 2 9 3 • First we must decide where • trades need to be made. The • trades can be made in any order. • Here we start with the ones • place. • Because 1 minus 3 results in a • negative number, we trade 1 ten • for 10 ones. Everyday Mathematics

  5. Trade-First Subtraction H T O 316 11 4 7 1 – 2 9 3 Solve: 471 – 293 • Next we look at the tens place. • Because 6 minus 9 results in a • negative number, we trade 1 • hundred for 10 tens. Everyday Mathematics

  6. Trade-First Subtraction H T O 316 11 4 7 1 – 2 9 3 1 7 8 • Solve: 471 – 293 • Now that all trades have been • made, we can subtract in any • place-value order. • 471 – 293 = 178 Everyday Mathematics

  7. Trade-First Subtraction When children use trade-first subtraction they practice a variety of skills related to number sense and algebraic reasoning. For example: • Writing numbers using place value; • Breaking a hundred into 10 [10s] and breaking a ten into 10 [1s]; and • Renaming numbers after shifting a group of 10 [10s] or 10 [1s] to the place-value column to the right. Everyday Mathematics

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