Borrowing Across Zeros

Handle borrowing when there are zeros

What You'll Learn

  • Borrow when tens digit is 0
  • Chain borrowing across zeros
  • Apply careful checking

📖Zeros Are Tricky

When you need to borrow but the next digit is 0, you must borrow from the digit after that. 500 - 137: Borrow from hundreds, making it 4 hundreds and 10 tens. Then borrow from tens to ones.

💡

When borrowing across a zero, the zero becomes 9 (because you borrowed 1 from it too)!