Add a Multiple of 100 to a 3-Digit Number
π 100, 200, 300... Blast off the final dial! Adding massive "zero" numbers is the easiest trick in second grade.
Do this: Read the concept below, then try the quiz or activity.
Concept
We already learned how to jump by 100s. This is the exact same trick!
π― The "Hundreds Only" Trick: Example: 425 + 300 = ?
Because 300 ends in TWO zeros... the Tens and Ones places of your starting number are completely safe. They won't change! 1. Cover up the Tens and Ones: Just look at the Hundreds. 4 + 3 = 7. 2. Put the 7 in the Hundreds place: The answer will start with a 7. 3. Bring back the frozen numbers! The "25" drops right back in where it was. So, 425 + 300 = 725!
It looks like a giant, scary problem. But you only solved "4 + 3 = 7".
Try it
Turn the Hundreds dial!
Instructions: Add the multiples of 100 by changing ONLY the Hundreds digit! Keep the back two digits frozen!
Problem 1: 512 + 200 = ? * Just add the hundreds! (5 + 2 = ___) * Keep the "12" frozen! * Answer: ___
Problem 2: 684 + 100 = ? * Answer: ___
Problem 3: 299 + 400 = ? * Answer: ___
Problem 4: 105 + 500 = ? * Answer: ___
Problem 5: 350 + 600 = ? * Answer: ___