Use compensation to subtract: up to three digits
š Subtraction compensation is a magic trick! If you slide BOTH numbers by the same amount, the difference stays the exact same.
Concept
Subtraction is about finding the difference (or distance) between two numbers. If you move both numbers the same amount on a number line, the distance between them doesn't change! šÆ **How Subtraction Compensation Works:** Unlike addition, in subtraction, you do the **SAME** thing to both numbers to keep the distance equal. **Example: 500 - 198 = ?** 198 is an ugly number to subtract. Let's make it a friendly 200. 1. **Shift the Number:** Add +2 to 198 to make it 200. 2. **Shift the Other Number:** You MUST add +2 to 500 to keep the distance the same! (It becomes 502). 3. **The New Problem:** 502 - 200. 4. **Subtract the Friendly Numbers:** 502 - 200 = 302! So, 500 - 198 = 302.
Try it
Slide the numbers to make the subtraction easy! **Instructions:** Shift BOTH numbers by the same amount to create a friendly problem. **Problem 1:** 400 - 199 * Add +1 to 199 to make 200. * Add +1 to 400 to make 401. * 401 - 200 = ___ **Problem 2:** 350 - 98 * Add +2 to 98 to make ___. * Add +2 to 350 to make ___. * Answer: ___ **Problem 3:** 600 - 295 * Answer: ___ **Problem 4:** 810 - 390 * (Hint: add +10 to both!) * Answer: ___