Mental skills
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•
Mathematics
•
2nd Grade
•
Hard
Ernie Dia
Used 16+ times
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10 Slides • 0 Questions
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Chapter 8 Mental skills
to go through and to review the concepts taught within the chapter.
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Making tens
58 is near to 60.
So, we can make 60 first.
58+8 is the same as
58+2 +6 or
60+6
60+6=66
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Adding or subtracting near multiples of 10 and adjusting.
18 and 2 make 20.
So, adding 18 is the same as adding 20 and then subtracting 2.
We add 20 to 44.
44 + 20=64
Then we subtract 2 from the result.
So, 44+18=62
Remember! When we add a 20, the digit in the tens place increases by 2.
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Regrouping into tens and units
9 and 1 make 10.
So, subtracting 9 is the same as subtracting 10 and then adding 1.
We subtract 10 from 25.
25-10= 15
Then, we add 1 to the result.
15 +1=16
So, 25-9=16 . Remember! When we subtract a 10, the digit in the tens place decreases by 1.
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You have learnt to add three small numbers by first making 20.
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You know to find doubles and halves of numbers mentally by regrouping the numbers into tens and units, finding their doubles or halves separately and then adding the results.
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Now, let's apply what you know. ,Let's do Putting it together 1 and 2.
Chapter 8 Mental skills
to go through and to review the concepts taught within the chapter.
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