K-5 friendly lesson
One small step at a time.Read the idea, try the activity, and celebrate each win as you go.
Subtract a 1-Digit from a 2-Digit (With Regrouping)
π¨ The ultimate subtraction trick! Borrowing! It's time to perform the "Smash a Ten" trick using only vertical numbers.
Do this: Read the concept below, then try the quiz or activity.
Lesson 57 of 186
Concept
This is the famous "Borrowing" trick that every math genius uses!
π― The Borrowing Code: Example: 42 - 6 = ? 4 2 - 6 -------- 1. "More on Top? No need to stop! More on the Floor? Go next door!" The 6 is on the floor, and it's bigger than 2! We can't do 2 - 6. Go next door! 2. Borrow from the neighbor: Look at the 4 (in the Tens place). Cross it out! Make it a 3. It lent you a Ten! 3. Give to the Ones: Give that 10 to the 2. Cross out the 2 and write an invisible little 1 in front of it to make it a 12. 4. Subtract the Ones: Now we can do it! 12 - 6 = 6. 5. Bring down the Tens: The neighbor is a 3 now. 3 - 0 = 3. 6. Answer: 36!
Try it
Go next door and borrow!
Instructions: Use the rhyme: "More on top? No need to stop! More on the floor? Go next door!"
Problem 1: 5 1 - 4 -------- * More on the floor? YES! 4 is bigger than 1. * Borrow from 5. (Make it a 4). Give to 1. (Make it an 11). * Ones: 11 - 4 = ___ * Answer: ___
Problem 2: 7 5 - 8 -------- * Answer: ___
Problem 3: 3 0 - 3 -------- * Answer: ___
Problem 4: 2 8 - 5 -------- * (Wait! More on top? No need to stop! Don't borrow on this one!) * Answer: ___