Subtraction Games that will teach your child to :
Mentally Add and Subtract 3(or more) digit numbers
The goal is for your child to mentally add/subtract numbers like: 620-322...your child may:
1. Start at the smallest number 322 and count up by 100's. 400, 500, 600 that is a total of 300 spaces. Next, I have to go backward 2 spaces, if I subtract 2 from 300, I get 298!
2. Start at the largest number: 620; count backwards by 100's then forward 2 spaces. That is 300 hundreds and then subtract 2...for the answer of 298.
3. The Old Fashioned Way: Borrow 1 from the tens column to make 10 in the ones column..that is 10-2; so I put an 8 in the ones column. Since I borrowed one from the tens column I am left with 1, so I need to borrow 1 from the hundreds column, that gives me 11-2; so I put a 9 in the tens column. Now I am left with 5-3, so I put a 2 in the hundred column. I am left with 298.
It takes a bit more time...but If your child is having difficulty you can build a 10,000 chart, using 10- 1000's charts. It takes a bit to put this together.... we keep our 10,000 chart up all the time in the house. It comes in handy when we discuss how big or small something is. It is extremely useful in understanding the number system.
Find Numbers When we use it , I will say "find 6540"." Subtract 300"." Subtract 40". "Subtract 2". "What did you get?" Do it faster and faster, if your child likes to compete, try timing them. It becomes a challenging race.
Once they can subtract thousands, hundreds, tens, and ones from each other you can play " Place Value Battle ship". Both you and your child can build a 10,000 chart. Secretly cross off 4-8 numbers without letting your opponent see ( these numbers become the "battle ships"). Each of you take turns saying numbers and seeing if you can hit the other persons "battle ships". If you get all of their "battle ships" (numbers) then you've been sunk!
The biggest challenge is making 2- 10,000's charts (use the blank 1000 chart below). The chart is pretty big when your done so my son and I tape our charts to each side of the door or a bookshelf to play.
We play "What's my Number". You pick a number and break it apart in thousands, hundreds, tens, ones and see if the other person can figure out your number. 20,000+3,000+200+40+1 Then your child chooses a number and you figure it out. Both of you will get speedy by the end of one round.
If your child has difficulty adding mentally, use a 300 chart as a tool to subtract numbers/ play subtraction games. Initially your child might count by ones, but the goal is for them to count by 10's , 100's - using the most efficient way possible.
NOTE: If your child is still struggling with 3 digit subtraction try 2 digits and work up slowly by playing more subtraction games.