A Pre-Algebra Module
Based on California State Math Standards -- Grade 7
Basics
Refresher
Remember back in the first and
second grade when you learned place value?
There was a reason.
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10
THOUSANDS |
THOUSANDS |
HUNDREDS |
TENS |
ONES |
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1 |
4 |
3 |
2 |
5 |
14,325
or fourteen thousand,
three hundred, twenty-five
We need place value when we do
any mathematical operation.
When we add, we think of the
place value boxes as houses where families live. The farther left you go the bigger the families.
Why?
Think about it. A 5 in the ones family means that there are five ones or just
plain 5.
A 5 in the tens family means
that there are 5 tens or 50.
The most important thing to
remember about these families is that the President of Place Value-Land has
passed a law.
PLACE
VALUE-LAND LAW: No house
will have more than 9 members.
Ah-ha!
This is why we must rename numbers.
If no house can have more than nine members, when we get a 10 or a 30 or
a 55…the right number stays home and the left number moves to the house on the
left.
Remember:
Right is right…left moves on!
Give
It A Try
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1 |
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4 |
6 |
8 |
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+ |
1 |
2 |
8 |
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6 |
Put your finger on the
RIGHT column. You have your finger
on 8 + 8. We know that 8 + 8 = 16.
16 is more than nine…so
the 10’s number…1…has to move next door.
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1 |
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4 |
6 |
8 |
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+ |
1 |
2 |
8 |
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6 |
Now, just finish the
problem:
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1 |
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4 |
6 |
8 |
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+ |
1 |
2 |
8 |
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5 |
9 |
6 |
JUST REMEMBER |
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You can only have 9 members of the same
family in one house! |