Study and remember the identity property that when adding or subtracting 0, the other number in the problem remains the same and is the answer. For example, 5 - 0 = 5 and 5 + 0 = 5.
Study and remember the rule that when adding 1 to a number, the sum becomes the next number on the number line, as in 5 + 1 = 6. Note that when subtracting 1 from a number, the difference becomes the number below it, as in 5 -- 1 = 4.
List and study fact families to understand the commutative property. Switch the order of the addends to find the same sum. Turn the addition problem into two subtraction problems. For example:
2 + 3 = 5
3 + 2 = 5
5 - 2 = 3
5 - 3 = 2
Write your addition and subtraction facts five times each in a notebook. Place a star next to the facts that are difficult to remember. Spend extra time studying those facts.
Create flash cards. Write one addition or subtraction problem on the front of each index card. Write the sum or difference on the back. Study and memorize one set of facts each week, starting with the zeros and continuing up to the nines. Study the cards daily for at least 10 minutes. Ask a friend to quiz you.
Place the flash cards of the addition and subtraction problems that you got incorrect in a pile. Rewrite those problems five times each and restudy.
Listen and sing along to addition and subtraction DVDs and CDs to memorize your facts. This helps you learn the facts similar to how you learn lyrics to songs.
Take a timed addition or subtraction quiz at the end of each week that focuses on one set of numbers. Give yourself one minute to complete an age-appropriate amount of problems such as 10 problems for first graders and 60 problems for fifth graders.
Correct your quiz and circle the addition and subtraction problems you missed. Rewrite these problems five times each and study the correlating flash cards and fact families.