Mixed Practice: 3-Digit Addition
⚡️ Lightning Round! Can you spot the tricks? Use compensation for the 9s, and Hundreds-dials for the zeros. Stack the rest!
Do this: Read the concept below, then try the quiz or activity.
Concept
You possess three different strategies for three-digit math.
🎯 The Strategy Selector: 1. The Dial Strategy: Does the number end in two zeros? (Like 400). Don't stack it! Just spin the hundreds dial in your brain! (235 + 400 = 635). 2. The Compensation Strategy: Does the number end in 98 or 99? Pretend it's a hundred! (+100, -1). 3. The Stacking Strategy: Is it a really messy number like 347? Grab your pencil and stack it up right away! Do NOT try mental math.
Try it
Pick your weapon!
Instructions: Look at the numbers before you start. Use the smartest trick possible!
Problem 1: 412 + 300 = ? * (Hey! It's two zeros! Just spin the hundreds dial!) * Answer: ___
Problem 2: 250 + 199 = ? * (Hey! It's a 99! Pretend it's 200, subtract 1!) * Answer: ___
Problem 3: 134 + 252 = ? * (Messy numbers! Stack them up!) 1 3 4 + 2 5 2 -------- * Answer: ___
Problem 4: 512 + 398 = ? * Answer: ___