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Published byGervase Dickerson Modified over 8 years ago
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Counting up to Subtract Addition and Subtraction are related! They are called inverse operations. Think back to your fact families. 4 + 5 = 9 9 - 5 = 4 5 + 4 = 9 9 - 4 = 5 I can start at the second number and count up! Try it!
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Ok…Those were to easy. Let’s try these! 456 - 167 Start at the second number and count up! Start with the ones…get to a ten! 167 + 3 = 170 168169 170 How many did I need to add to get to the ten?
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Ok…Those were to easy. Let’s try these! 456 - 167 Start at the second number and count up! Start with the ones…get to a ten! 167 + 3 = 170 168169 170 How many did I need to add to get to the ten? 180 Now let’s count by tens…get to a hundred! 190 200 How many did I need to add to get to the hundred? 170 + 30 = 200
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Ok…Those were to easy. Let’s try these! 456 - 167 Start at the second number and count up! Start with the ones…get to a ten! 167 + 3 = 170 168169 170 How many did I need to add to get to the ten? 180 Now let’s count by tens…get to a hundred! 190 200 How many did I need to add to get to the hundred? 170 + 30 = 200 Now let’s count by hundreds… get to 400! 300400 How many did I need to add to get to 400? 200 + 200 = 400
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Ok…Those were to easy. Let’s try these! 456 - 167 Start at the second number and count up! Start with the ones…get to a ten! 167 + 3 = 170 168169 170 How many did I need to add to get to the ten? 180 Now let’s count by tens…get to a hundred! 190 200 How many did I need to add to get to the hundred? 170 + 30 = 200 Now let’s count by hundreds… get to 400! 300400 How many did I need to add to get to 400? 200 + 200 = 400 Now I just need to get from 400 to 456. From 00 to 56 is…..56!
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Ok…Those were to easy. Let’s try these! 456 - 167 Start at the second number and count up! Start with the ones…get to a ten! 167 + 3 = 170 168169 170 How many did I need to add to get to the ten? 180 Now let’s count by tens…get to a hundred! 190 200 How many did I need to add to get to the hundred? 170 + 30 = 200 Now let’s count by hundreds… get to 400! 300400 How many did I need to add to get to 400? 200 + 200 = 400 Now I just need to get from 400 to 456. From 00 to 56 is…..56! To find my answer, now I just add up everything I added! 200 30 3 + 56
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Ok…Those were to easy. Let’s try these! 456 - 167 Start at the second number and count up! Start with the ones…get to a ten! 167 + 3 = 170 168169 170 How many did I need to add to get to the ten? 180 Now let’s count by tens…get to a hundred! 190 200 How many did I need to add to get to the hundred? 170 + 30 = 200 Now let’s count by hundreds… get to 400! 300400 How many did I need to add to get to 400? 200 + 200 = 400 Now I just need to get from 400 to 456. From 00 to 56 is…..56! To find my answer, now I just add up everything I added! 200 30 3 + 56 289
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Most of what we wrote you can do in your head. Your work should look like this. 456 - 167 167 + 3 = 170 170 + 30 = 200 400 + 56 = 456 200 + 200 = 400 Make sure you line it up!!! 200 30 56 + 3 289
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Most of what we wrote you can do in your head. Your work should look like this. Let’s copy this part into our journals. 456 - 167 289 167 + 3 = 170 170 + 30 = 200 400 + 56 = 456 200 + 200 = 400 200 30 56 + 3 289
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Try this one. 845 - 384 384 + 6 = 390 Hint: start with the bottom number. Count by ones. Stop at the first ten. Add on by: ones tens hundreds final number
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Try this one. 845 - 384 384 + 6 = 390 390 + 10 = 400 Hint: start at 390. Count by tens. Stop at the first hundred.
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Try this one. 845 - 384 384 + 6 = 390 390 + 10 = 400 400 + 400 = 800 Hint: start at 400. Count by hundreds. Stop at 800. (Look at your top number to see why.)
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Try this one. 845 - 384 384 + 6 = 390 390 + 10 = 400 800 + 45 = 845 400 + 400 = 800 Hint: start at 800. Stop at 45. (Look at your top number to see why.)
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Try this one. 845 - 384 384 + 6 = 390 390 + 10 = 400 800 + 45 = 845 400 + 400 = 800 Hint: Line them up! Then, add! 400 45 10 + 6 1 1 64
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Try this one. 845 - 384 461 384 + 6 = 390 390 + 10 = 400 800 + 45 = 845 400 + 400 = 800 400 45 10 + 6 461
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More practice. 173 - 34 492 - 347 722 - 581 192 - 17 1,022 - 347 4,642 - 1,874
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More practice. 173 - 34 139 492 - 347 722 - 581 192 - 17 1,022 - 347 4,642 - 1,874
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More practice. 173 - 34 139 492 - 347 145 722 - 581 192 - 17 1,022 - 347 4,642 - 1,874 Do the rest with paper and pencil by yourself. I might ask you to come work with me on the floor.
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Put up your pencil and get out your red pen!
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More practice. 173 - 34 139 492 - 347 145 722 - 581 141 192 - 17 175 1,022 - 347 675 4,642 - 1,874 2,768
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