Subtraction with Regrouping: 991,233 − 3,579

• Ones: 3 is less than 9 — borrow 1 ten: tens 3 → 2; 13 − 9 = 4 — write 4.
• Tens: after borrowing, 2; 2 is less than 7 — borrow 1 hundred: hundreds 2 → 1; 12 − 7 = 5 — write 5.
• Hundreds: after borrowing, 1; 1 is less than 5 — borrow 1 thousand: thousands 1 → 0; 11 − 5 = 6 — write 6.
• Thousands: after borrowing, 0; 0 is less than 3 — borrow 1 ten thousand: ten thousands 9 → 8; 10 − 3 = 7 — write 7.
• Ten thousands: after borrowing, 8; nothing to subtract — write 8.
• Hundred thousands: nothing to subtract — write 9.

991,233 − 3,579 = 987,654

Second check: 991,233 − 987,654 = 3,579