Regrouping
When you are subtracting double digit numbers, how do you know when you need to regroup?
Math the correct answer:
1.)When you are adding on a number line you jump to the ________
2.) When you are subtract on a number line you jump to the ________
a.) Left
b.) Right
1.) B right
2.) A Left
Some oranges are in a box. Marc takes 21 oranges out of the box. Now there are 56 oranges in the box. How many oranges were in the box to begin with?
_?_ - 21 = 56
56 + 21 = _?_
There were 77 oranges in the box to start.
21 - 17 = 16
No, she forgot to regroup when she subtracted. The correct answer is 4. You can check your work by adding. 17 + 16 = 33
Solve the equation:
21 - 9 = _?_
12
Use a number line to solve this equation.
75 - 23 =
52
There are 56 students at the park. There are 34 girls at the park. How many fewer boys are at the park than girls?
56 - 34 = 22
There are 22 fewer boys at the park than girls.
Read the word problem. Andrew solved the problem at put his answer into a sentence. Is he correct? Explain.
Lilly has a bag of prizes. Her friends take 38 prizes from the bag. Now there are 16 prizes in the bag. How many prizes did Lilly have at the start?
Lilly had 22 prizes at the start.
Andrew is not correct. He should have added, but he subtracted instead. The correct answer 54.
Solve the equation:
54 - 27 = _?_
27
Use a number line to solve this equation.
83 - 49 = _?_
34
A store has some 72 items of clothes for sale. People buy 31 coats from the store. Then people buy 12 dresses. How many items of clothing is left at the store?
step 1 : 72 - 31 = 41
step 2 : 41 - 12 = 29
There are 29 items of clothing left at the store.
Madelyn shows her work to sole this problem. Is she correct. Where did she go wrong? What is the correct answer?
Santi has some 35 pencils. Marc takes 7 pencils from Santi. Then Drew gives Santi 15 more pencil. How many pencils does Santi have now?
Step 1: 35 - 7 = 28
Step 2: 35 + 15 = 50
Santi has 50 pencils in the end.
Madelyn is not correct. In step 2 she didn't include the sum that she already found. She should have been adding 15 to 28.
Step 1: 35 - 7 = 28
Step 2: 28 + 15 = 43
Santi has 43 pencils in the end.