Use compensation to add: up to three digits
āļø Want to do mental math like a wizard? Use "compensation" to turn ugly numbers into friendly ones before you add!
Concept
Sometimes adding big numbers looks scary, like 398 + 245. But 398 is extremely close to a "friendly" number (400!). We can use compensation to make it easier. šÆ **How Compensation Works:** Think of addition like a balance scale. If you add weight to one side, you must take it away from the other side. **Example: 398 + 245 = ?** 1. **Make a Friendly Number:** 398 needs just 2 more to become 400. 2. **Borrow from the Other Number:** If I add +2 to 398, I must subtract -2 from 245. 3. **The New Problem:** (398 + 2) = 400 (245 - 2) = 243 4. **Add the Friendly Numbers:** 400 + 243 = 643! So, 398 + 245 = 643.
Try it
Turn these ugly problems into friendly ones! **Instructions:** Adjust the numbers to make the addition easier, then solve. **Problem 1:** 199 + 350 * 199 needs 1 to become 200. * Subtract 1 from 350 (it becomes ___). * Add: 200 + ___ = ___ **Problem 2:** 495 + 120 * 495 needs 5 to become 500. * 120 minus 5 is ___. * Add: 500 + ___ = ___ **Problem 3:** 298 + 104 * Evaluate and Answer: ___ **Problem 4:** 990 + 35 * Evaluate and Answer: ___