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Use partial differences

For subtraction of whole numbers within 1,000, the learner decomposes the numbers into hundreds, tens, and ones, finds the corresponding place-value differences, and combines those partial results to determine the total difference. The reasoning includes regrouping when a place-value part of the minuend is too small, while maintaining equivalence between the decomposed and original quantities; more advanced algorithms, larger numbers, and generalized negative-number methods are not included.

Detailed Explanation: Use partial differences

To use partial differences, break each number into hundreds, tens, and ones. Then subtract each place-value part and combine the answers.

Example:

463−278463-278

First decompose the numbers:

463=400+60+3463=400+60+3 278=200+70+8278=200+70+8

The ones part, 33, is too small to subtract 88. Regroup one ten as 1010 ones:

400+60+3=400+50+13400+60+3=400+50+13

Now the tens part, 5050, is too small to subtract 7070. Regroup one hundred as 100100 tens:

400+50+13=300+150+13400+50+13=300+150+13

The amount is still 463463; it is just written in a different way.

Now find the partial differences:

  • Hundreds: 300−200=100300-200=100
  • Tens: 150−70=80150-70=80
  • Ones: 13−8=513-8=5

Combine the partial differences:

100+80+5=185100+80+5=185

Therefore,

463−278=185463-278=\boxed{185}

Learn by doing: Use partial differences

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Subtraction - Whole Number 3 x 2, With Borrow


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