1. How to Subtract two-digit numbers with regrouping By: Melissa Collins

2. How do you know when to subtract? In order to subtract, you need to decide if you need to regroup. To decide if you need to regroup follow these 8 steps.

3. Step 1 You look at the problem and look to see if it is a subtraction problem. If it is, move to step 2. 2 4 - 1 3

4. Step 2 If it is a subtraction problem you always start in the ones column. If the bottom number is bigger then you must regroup. 3 4 - 1 7

5. Step 3 If the bottom number isn’t bigger then you just subtract the ones. 2 6 - 1 4

6. Step 4 If the bottom number is bigger then you need to knock on Mr. Ten’s door. Ask Mr. Ten if you can borrow one ten.

7. Step 5 When you borrow one ten from Mr. Ten you cross out the number in the tens and subtract 1 away from that number. Now, write the new number above the number that you crossed out. 2 3 4 - 1 7

8. Step 6 Since you borrowed a ten, you now add 10 to the top number in the ones column. So, instead of 4 ones you now have 14 ones. Next, cross out the 4 and write 14 above it. You can also simply just write a 1 in front of the 4 to make it 14. 2 14 3 4 -1 7

9. Step 7 Now you can subtract the ones. If you have 14, and you give me 7, how many will you have left? 2 14 3 4 - 1 7 7

10. Step 8 After you subtract the ones, look at the bottom number in the tens column. If that number is smaller than the top number, then subtract the tens. 2 14 3 4 - 1 7 1 7

11. It’s your turn to practice! Remember you always start in the ones. You look at the bottom number, if the bottom number is bigger than you must regroup.

12. Question 1 4 7 - 2 9 A.2222 B.2828 C.1818

13. Question 2 5 3 - 2 1 A.2222 B.2323 C.3232

14. Question 3 3 3 - 1 5 A.1818 B.2222 C.4848

15. Are you a Star Mathematician? You’re a Star Mathematician if all your answers are correct. If 2 out of 3 problems are correct, then, your on your way to being a Star Mathematician. In order to be a Star Mathematician you need to practice 2 subtraction problems daily. If 1 or none are correct out of 3, you need to practice, practice, and practice to be a Star Mathematician. You need to do 4 subtraction problems daily.

16. Nice Try Sorry but you missed that one. Go back and take another look. Question 1 Question 2 Question 3

17. Congratulations Great job! Keep up the good work! Question 2 Question 3 I answered all 3 questions.