What is the Bridging Strategy?

S1-SA1-0730

Grade Level:

Class 3

Maths, Computing, AI, Mental Maths

Definition

What is it?

The Bridging Strategy is a mental math technique used to add or subtract numbers by 'bridging' over a multiple of 10. It involves breaking one of the numbers into parts to reach the nearest 10, making the calculation easier. This strategy helps simplify complex sums and differences.

Simple Example

Quick Example

Imagine you have 7 laddoos and your friend gives you 5 more. To find the total using the bridging strategy, you first think: '7 needs 3 more to become 10'. So, you take 3 laddoos from your friend's 5. Now you have 10 laddoos. The remaining laddoos from your friend are 5 - 3 = 2. So, 10 + 2 = 12 laddoos in total.

Worked Example

Step-by-Step

Let's add 8 + 6 using the Bridging Strategy:

Step 1: Identify the larger number. Here, it's 8.
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Step 2: Think: 'How much more does 8 need to reach the next multiple of 10?' 8 needs 2 more to reach 10.
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Step 3: Break the second number (6) into two parts. One part is the 'bridge' number (2), and the other part is the remainder. So, 6 becomes 2 + 4.
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Step 4: Add the larger number (8) to the 'bridge' number (2). 8 + 2 = 10.
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Step 5: Add the result (10) to the remaining part of the second number (4). 10 + 4 = 14.
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Answer: So, 8 + 6 = 14.

Why It Matters

This strategy is super useful for quick mental calculations, which is like having a mini-calculator in your head! It's a foundation for understanding how computers process numbers quickly (in Maths and Computing) and is even used in basic AI algorithms for efficient problem-solving. Knowing this helps you think logically and solve problems faster in daily life and future careers like data analysis or software development.

Common Mistakes

MISTAKE: Not breaking the second number correctly. For 7 + 5, students might try to bridge 5 to 10 instead of 7. | CORRECTION: Always bridge the number that is closer to the next multiple of 10, or the larger number, to simplify.

MISTAKE: Forgetting to add the remaining part after bridging to 10. For 8 + 6, they might do 8 + 2 = 10 and stop. | CORRECTION: Remember that you broke the second number into two parts. After adding the first part to reach 10, you must add the remaining part.

MISTAKE: Applying the strategy only for addition. | CORRECTION: The bridging strategy can also be used for subtraction. For example, 15 - 7: first subtract 5 to reach 10 (15 - 5 = 10), then subtract the remaining 2 (7 - 5 = 2) from 10 (10 - 2 = 8).

Practice Questions

Try It Yourself

QUESTION: Use the Bridging Strategy to add 9 + 4. | ANSWER: 9 needs 1 to reach 10. Break 4 into 1 + 3. So, 9 + 1 = 10. Then 10 + 3 = 13.

QUESTION: A bus had 17 passengers. 6 more passengers got in. How many are there now, using the Bridging Strategy? | ANSWER: 17 needs 3 to reach 20. Break 6 into 3 + 3. So, 17 + 3 = 20. Then 20 + 3 = 23 passengers.

QUESTION: Subtract 14 - 8 using the Bridging Strategy. | ANSWER: 14 - 4 = 10 (bridged to 10). Remaining to subtract is 8 - 4 = 4. So, 10 - 4 = 6.

MCQ

Quick Quiz

Which step is correct when using the Bridging Strategy to add 7 + 8?

Break 8 into 7 + 1

Add 7 + 3 to get 10, then add the remaining 5

Add 8 + 2 to get 10, then add the remaining 5

Break 7 into 4 + 3

The Correct Answer Is:

For 7 + 8, we bridge 7 to 10. 7 needs 3 more to reach 10. So, we take 3 from 8 (leaving 5). Then, 7 + 3 = 10, and 10 + 5 = 15. Option B correctly describes this process.

Real World Connection

In the Real World

When you're quickly calculating how much change to give back at a shop, or estimating the total cost of groceries without a calculator, you're often using the bridging strategy mentally. Even delivery apps like Zomato or Swiggy use similar logic in their backend systems to quickly estimate delivery times by breaking down travel into simpler segments.

Key Vocabulary

Key Terms

BRIDGING: The act of reaching a multiple of 10 (like 10, 20, 30) during a calculation. | MENTAL MATH: Doing calculations in your head without writing them down. | MULTIPLE OF 10: Numbers like 10, 20, 30, 40, etc. | DECOMPOSITION: Breaking a number into smaller parts to make a calculation easier.

What's Next

What to Learn Next

Great job learning the Bridging Strategy! Now you're ready to explore 'Compensation Strategy'. It's another mental math trick that builds on bridging, helping you solve even bigger addition and subtraction problems super fast. Keep practicing!