Mentally add 2 and 3 digit numbers

34+26=

WHAT THE HECK IS MENTAL MATH?

Here is an example of one possible way they are thinking while adding two or three digit numbers:

62+34= (So...first I start at the biggest number ,62- I make it easy to add ( I call this making a number friendly) by making it 60, then I take , 34-and make it 30 , 60 and 30 is like 6+3, which is 9 then, I add the zero. Next I add the ones, 4+2 and get 6, so, I had 90 and now I add 6, the answer is 96!

Are you thinking...that is alot of work to add two numbers? You have to trust me on this one, this process takes milliseconds once it is learned.

If your child has difficulty adding mentally, use a hundreds chart and have them find 62 then count up 34. Now initially your child might count by ones, but the goal is for them to count by 10's or count the most efficient way possible

If your child can add 2 digit and 2 digit numbers, they are ready to add 2 digits to three and four digit numbers. Try using the 300's chart and 1000 chart while adding these large numbers to develop a sense of larger numbers.

The goal is for your child to mentally add numbers like: 2340 +33 and 345 + 21. Their thinking will be something like this: 2340+33 , starting at the largest number, 2340 I can up 3 tens(2340+10+10+10=2370), count up 3 ones (2370+3)= for a total of: 2373

1. Build  a 10,000 chart, 10- 1000 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. We use it to play simple addition games: I will say "find 6540"." Add 300"." Add 40". "Add 2". "What did you get?" Do it faster. It becomes a challenging race. It is also a great homework helper!

2. Once they can add thousands, hundreds, tens, and ones together you can play "Place Value Battle ship" (this is one of our favorite addition games although it takes a little preparation) . Both you and your child build a 10,000 chart (my son puts his his 10,000 chart on one side of a bookshelf or door and I put mine on the other side. Secretly cross off 4-8 numbers without letting your opponent see. Each of you take turns say numbers and seeing if you can hit the other persons numbers they chose. If you get all 4 of their numbers then you've been sunk!

3. We play "What's my Number" anywhere. 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.

4. Take it to the next step. When you are adding up numbers, take advantage of the addition strategies you already know. For example, when I am adding 63+62, I would start at 60 and count up 60. I could also use the addition strategy I know, I know that 6+6 is 12, so I could add a zero to 12 and get 120. Another example, 45+32, I add the tens 40+30 ( which is 4+3, I know that 3+3 is 6 add one more for 7).

5. Have your child think of their own addition games with their chart!