Adding Subtracting Whole Numbers and Money The number

Adding & Subtracting Whole Numbers and Money

The number obtained by adding numbers is the…

The number obtained by subtracting one number from another is the…

Addition and Subtraction Patterns Use basic facts to help you add and subtract tens, hundreds, and thousands mentally.

Now it’s your turn! 1. 2. 3. 4. 5. 6. 7. 3+5= 30 + 50 = 300 + 500 = 13 – 9 = 130 – 90 = 1, 300 – 900 = ____ - 9, 000 = 4, 000

n + 30, 000 = 90, 000 n = 60, 000

$90. 00 – n = $50. 00 n = $40. 00

Estimate means… to find a number close to the exact number.

Rounding to Estimate Sums Round each addend. Then find the estimated sum.

Rounding to Estimate Differences (Round to the nearest hundred. ) Round each number. Then find the estimated difference.

Now it’s your turn! 1. 2. 3. 4. 5. 6. 7. 567 + 241 600 + 200 = 800 674 – 221 700 - 200 = 500 8, 000 + 2, 000 = 10, 000 7, 881 + 1, 589 4, 000 - 2, 000 = 2, 000 3, 580 – 1, 625 385 + 251 400 + 300 = 700 80, 000 - 30, 000 = 50, 000 80, 021 – 32, 679 60, 000 + 20, 000 = 80, 000 55, 427 + 18, 149

Exact answer or Estimate? 1. If 10 pizzas serve 80 students, how many will 30 pizzas serve? 2. The cafeteria served 305 lunches last week. This week they served 28 more lunches. How many did they serve?

Adding with Regrouping Add the ones and regroup as needed. 1

Adding with Regrouping Add the tens and regroup as needed. 1

Adding with Regrouping Add the hundreds and regroup as needed. 1 1

Adding with Regrouping Add the thousands. Estimate to check. 1 1

Get a piece of paper and practice! 1. 84 + 31 = 2. 986 + 85 = 3. 402 + 290 = 4. 3, 094 +, 8, 371 = 5. 650 + 772 =

Front-end estimation is… A way to estimate by first looking at the leading digits.

Front-End Estimation Example Look at the leading digits only.

Column Addition Add the ones first. Then add the tens. Move on to the hundreds and then the thousands. 1 1

Subtraction with Regrouping Subtract the ones and regroup as needed. 4 13

Subtraction with Regrouping Subtract the tens and regroup as needed. 4 13

Subtraction with Regrouping Subtract the hundreds and regroup as needed and then subtract the thousands. 8 10 4 13

Subtraction with Regrouping Remember! You can only borrow and regroup from the next place. For example, ones can only borrow from the tens place. Tens can only borrow from the hundreds place and so on.

Get a piece of paper and pencil! 1. 700 – 382 = 318 Check: 318 + 382 = 700 2. 2, 000 – 1, 248 = 752 Check: 752 + 1, 248 = 2, 000 7, 004 – 373 = 6, 631 Check: 6, 631 + 373 = 7, 004 5, 000 – 3, 553 = 1, 447 3. 4. Check: 1, 447 + 3, 553 = 5, 000

Multi-Step Problem Solving Follow these easy steps to solve problems with more than one step.

Gayle’s first draft of a story had 212 words. When she edited the story, she crossed out 24 words and added 47 new ones. How long was her story when she finished? n Step 1: Understanding the question: n What do you know? I know she started with 212 words, she crossed out 24 of them, and she added 47 more. n What do you need to find out? I need to know how long the story was when she was done.

Gayle’s first draft of a story had 212 words. When she edited the story, she crossed out 24 words and added 47 new ones. How long was her story when she finished? n Step 2: Planning: n How can you find out? First, find out how long the story was after she crossed out the 24 words. n What is the next step? Then find out how long the story was after she added the 47 new words.

Gayle’s first draft of a story had 212 words. When she edited the story, she crossed out 24 words and added 47 new ones. How long was her story when she finished? n Step 3: Solving the Problem: n Subtract to find the length of the story after she crossed out the words. (Do this now. ) 212 – 24 = x n Add the new words to your answer. (Do this now. ) 188 + 47 = y

Gayle’s first draft of a story had 212 words. When she edited the story, she crossed out 24 words and added 47 new ones. How long was her story when she finished? n Step 4: Looking Back: n Does your answer (235) make sense? Yes! You can estimate to check your answer. 212 – 24 = 188 + 47 = 235 n How do you know? My answer is close to my estimate.

Gayle’s first draft of a story had 212 words. When she edited the story, she crossed out 24 words and added 47 new ones. How long was her story when she finished? Gayle’s story was

Kyle’s 1 st story was 117 words long. His 2 nd story was 42 words longer. His 3 rd story is 56 words shorter than his 2 nd story. How long is his 3 rd story? Solve this on a separate sheet of paper now.

Jen uses a computer for one hour. She spends 26 minutes writing a story and 21 minutes correcting it. How much time does she have left? Solve this on a separate sheet of paper now.

Counting Money n How much money is here?

Counting Money n How much money is here?

Counting Money n How much money is here?

Adding Money: Find $2. 25 + $1. 10. n Step 1: Line up the decimals.

Adding Money: Find $2. 25 + $1. 10. n Step 2: Add as you would with whole numbers.

Adding Money: Find $2. 25 + $1. 10. n Step 3: Write the decimal and dollar sign in the sum.

Paper! Pencil! Practice! 1. $9. 94 - 2. 10 = 2. $10. 59 – 2. 35 = 3. $15. 38 + 22. 95 = 4. $6. 42 + 13. 16 =

Making Change! n First find the cost. Add together the cost of each item you are buying to find the TOTAL cost. n Now, find the change. Subtract the total cost from the amount you are paying with.

You buy 22 books for $3. 99 each. You pay with two $5 bills. . What is your change? n First find the cost. Add together the cost of each item you are buying to find the TOTAL cost. n Now, find the change. Subtract the total cost from the amount you are paying with.

A customer buys a toy boat for $9. 49 and stickers for $1. 79. She pays with a $20 bill. What is her change? n First find the cost. n Now, find the change.

Balancing Number Sentences n How do you know when a number sentence is balanced? The value of the left side equals the value of the right side.

n + 6 = 11 What number do I add to 6 to make it equal 11? 11 - 6 5

12 + n = 18 What number do I add to 12 to make the sum 18? 18 - 12 6

23 = 7 + n What number do I add to 7 to make it equal 23? 23 - 7 16

214 = n + 185 What number do I add to 185 to make it equal 214? 214 - 185 29

10 = 12 - n What number do I subtract from 12 to get a difference of 10? 10 + 2 12

Look for the pattern What is the rule for this pattern? Add one side to the shape each time.

Look for the pattern +3 -1 +3 What is the rule for this pattern? Go ahead 3 letters, then back 1 letter in the alphabet. Continue the pattern two more letters.

Look for the pattern x 2 x 2 What is the rule for this pattern? Double the number. Continue the pattern two more numbers.

The test is on November 15, 2007. The most challenging concepts are: n Making change n Subtracting with regrouping n Multi-step problem solving The most common mistakes made are: n Not showing your work n Not checking answers n Not labeling n Not reading the directions carefully