Learn some math tricks to help with addition and subtraction.
We will learn these strategies in class, also.
1. Know your doubles
2. The "Human" Number Line
Start with the biggest number and add on using a number line.
3. Order property: The order of the numbers in anaddition problem does not change
7+12 = 12+7
Both of these sums are the same! The answer is 19!
4. Doubles plus one: You can figure the sum of 7+8 if you know your double 7+7=14.
Just add one more to the answer because 8 is one more than 7.
7+8 = 7+7+1
5. Adding Ten is easy: When you add a number to ten, just take out the "0" in the
number 10 andreplace it with the number you are adding to it.
6. Make a nine a ten. It is faster when adding if you make a ten out of the problem.
9+6 is the same as 10+5
9+7 is the same as 10+6
9+8 is the same as 10+7
Remember what these mean also...
+ to add
- to take something away
= is the same as
You will learn some strategies in class to help you subtract quickly.
Practice them at home until you know them by heart.
1. Know your fact families to help you find an answer.
The fact family 3,7,4 has three members in it. They are:
You can use it to help you find the answer to the following problem.
7-3 = ? What number plus 3 will equal 7?
2. Subtract nothing from a number and the number stays the same.
8 - 0 = 8 9-0=9 4-0=4
3. Use a number line to count back to find the answer.
9 - 5 = ?... Start at 9 and count back 5 spaces on the number
line.The answer will be four.
4. Use a number line to count forward to find the answer.
6-4=2 Start with the smaller number in the number
sentence. In the number sentence 6-4,
start with 4 on the number line and
count up to six. How many jumps up the number
line did you make to arrive at the number 6?
That's the answer. You jumped two numbers
up the line so the answer is 2.
5. Remember that the largest number always goes first when subtracting.