Learning Objectives
- Add two-digit numbers with carrying (regrouping)
- Add three numbers together
- Solve word problems involving addition
- Check addition using subtraction
- Use addition in simple games and activities
Key Concepts
Addition with Carrying
Sometimes when we add the ones, we get a number bigger than 9. Then we need to carry the extra ten to the tens column. For example, 27 + 15: Add ones: 7 + 5 = 12. Write 2 in ones place and carry 1 to tens place. Add tens: 2 + 1 + 1 (carried) = 4. The answer is 42.
Adding Three Numbers
We can add three numbers step by step. First add two numbers, then add the third. For example, 12 + 15 + 21: First, 12 + 15 = 27. Then, 27 + 21 = 48. The total of all three numbers is 48.
Addition in Games
Many games use addition. When we throw two dice, we add the numbers to find our score. If one die shows 4 and the other shows 5, our score is 4 + 5 = 9. If we play three rounds with scores 12, 15, and 8, our total score is 12 + 15 + 8 = 35.
Checking Our Answer
We can check an addition answer using subtraction. If 25 + 18 = 43, we check by subtracting: 43 − 18 = 25. Since we get back the first number, our addition is correct. This is a good habit to make sure we do not make mistakes.
Word Problems
Sita scored 24 points in the first game and 19 points in the second game. What is her total score? We add: 24 + 19. Ones: 4 + 9 = 13, write 3 carry 1. Tens: 2 + 1 + 1 = 4. Total = 43 points.
Important Terms
- Carrying (Regrouping): Moving an extra ten from the ones column to the tens column
- Score: Points earned in a game
- Total: The answer when all numbers are added together
- Check: Making sure the answer is correct by using the opposite operation
- Dice: Small cubes with dots (1 to 6) used in games
Quick Revision
- When ones add up to more than 9, carry the ten to the tens place
- To add three numbers, first add two, then add the third
- Check addition by subtracting: if a + b = c, then c − b = a
- Games like dice use addition to count scores
- Practice: 28 + 14 = 42, 36 + 27 = 63, 15 + 19 + 8 = 42
- Read word problems carefully to find the numbers to add