2. Everyday Mathematics Trade-First Subtraction

3. 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

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

5. Trade-First Subtraction Everyday Mathematics Solve: 471 – 293 HTO 611 471 – 293 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.

6. Trade-First Subtraction HTO 31611 471 – 293 Everyday Mathematics 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.

7. Trade-First Subtraction HTOHTO 31611 471471 – 293 178178 Everyday Mathematics Solve: 471 – 293 Now that all trades have been made, we can subtract in any place-value order. 471 – 293 = 178

8. 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