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The Trade First Algorithm is an innovative two-stage process designed to simplify the subtraction of multi-digit numbers. Developed by Paula Cantera at Elk Neck Elementary, this method allows students to borrow from higher place values effectively. First, students work from right to left to perform all necessary borrowing. Next, they can subtract in any order. For example, in the problem 325 - 58, students will trade tens and hundreds for ones to make the subtraction manageable. This method promotes flexibility in calculations and enhances number sense.
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Trade First Algorithmfor Subtraction Created by Paula Cantera Elk Neck Elementary
The trade first algorithm is a two stage process. • First, working right to left do all of the borrowing. • Next, in any order, do the subtractions
325 - 58 In the problem above you see that the ones column needs borrowing.
1 15 (10 + 5) 325 - 58 We will trade in one of the tens for ten ones.
1 15 325 - 58 We also see that the tens column needs borrowing .
11 (10 + 1) 2 1 15 325 - 58 We will trade in one of the hundreds for ten tens.
11 2 1 15 325 - 58 You are now ready to subtract. You can do the subtractions in any order.
11 2 1 15 15 - 8 = ? 325 - 58 11 - 5 = ? 2 - 0 = ? 2 6 7
Or we could do it in this order.. 11 2 1 15 2 - 0 = ? 325 11 - 5 = ? - 58 15 - 8 = ? 2 6 7
Trade First Algorithm for Subtraction • Another way to subtract multi-digit numbers. Try it!
