Hi! I'm Vidi. Let's learn Addition Strategies together — read with me, then play the games to win a ⭐!
🔵Addition Strategies
Addition is not just about writing columns on paper; it is also about finding clever shortcuts in your head! Addition strategies help you solve math problems mentally, quickly, and accurately without needing to count one-by-one on your fingers.
- Counting On from the Larger Number: Instead of starting from zero, keep the larger number in your head and count forward using the smaller number. For example, to solve 3 + 42, start at 42 and count up three times: 43, 44, 45.
- Compensation Strategy (Making a Ten): Zeros are easy to add! If a number is close to a friendly ten (like 9, 18, or 29), steal a small amount from the other number to turn it into a ten, then add the rest. For example, to solve 29 + 6, move 1 from the 6 over to the 29 to make it 30 + 5 = 35.
- Doubles and Near-Doubles Reinforcement: * Doubles are numbers added to themselves (like 6+6=12 or 8+8=16).
- Near-Doubles use your doubles facts to solve nearby problems. For example, to solve 7 + 8, think of it as (7 + 7) + 1 = 14 + 1 = 15.
- Adding 10 or 100 Mentally: * Adding 10 increases only the tens digit by exactly 1 (345 + 10 = 355).
- Adding 100 increases only the hundreds digit by exactly 1 (345 + 100 = 445).
- Solving 1-Step and 2-Step Word Problems: Applying these exact shortcuts to solve real-world stories.
- 1-Step problems require one single calculation.
- 2-Step problems require you to find a hidden intermediate total first before calculating your final answer.
👀 See a worked example
Use a near-doubles mental strategy to solve the addition expression: 6 + 7.
- Look at the two numbers. They are right next to each other on the number line.
- Recall your smaller doubles fact: 6 + 6 = 12.
- Since 7 is exactly 1 more than 6, add 1 to your doubles total.
Answer: 13
🤖 Vidi's Key Points
- Counting on is fastest when you keep the *larger* number in your head first, even if it is written second (2 + 84 \rightarrow start at 84 and count 85, 86).
- The compensation strategy makes addition simple by building friendly tens numbers ending in 0.
- Near-doubles converts an unfamiliar addition problem into a double fact plus or minus 1.
- Adding 10 or 100 changes only that specific place-value digit, leaving the other columns untouched.
🎯 Mission Test
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