Addition and Subtraction

This lesson provides an introduction to the addition and subtraction of one-, two-, and three-digit numbers, utilizing real-life scenarios like calculating grocery bills.Addition

• One-Digit Numbers: The process begins with simple addition, such as 5 + 7 = 12 or 8 + 2 = 10.
• Two-Digit Numbers: To add two-digit numbers, one adds the digits in the ones place first, followed by the tens place.
  • For example, 14 + 23 equals 37.
  • Techniques include regrouping (e.g., 16 + 22 = 38) and carrying (e.g., 29 + 44 = 73).
• Three-Digit Numbers: The process extends to three-digit numbers by adding the ones, then the tens, and finally the hundreds place.
  • An example without carrying is 143 + 254 = 397.
  • An example with carrying is 423 + 287 = 710.

Subtraction

• One-Digit Numbers: Subtraction is demonstrated using everyday objects, such as having four chapatis and eating three, leaving one. Similarly, 12 notebooks minus 7 leaves 5.
• Two-Digit Numbers: The operation involves subtracting the ones place first, then the tens place.
  • Standard subtraction: 25 – 12 = 13.
  • Regrouping: 34 – 9 = 25 and 54 – 18 = 36.
  • Borrowing: 65 – 27 = 38.
  • Word problem application: Starting with 50 rupees and spending 36 leaves 14.
• Three-Digit Numbers: This follows the same column-based method with borrowing.
  • An example without borrowing is 364 – 241 = 123.
  • An example involving borrowing is 754 – 227 = 527.

The lesson concludes by summarizing that two- and three-digit arithmetic relies on the fundamental techniques of regrouping, carrying, and borrowing.