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T (MATH) m
Mathematics
Basic Addition and Subtraction
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Vocabulary
Digit: Any number 1 through 9 and 0 (e.g., the number 7 is a digit).
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Place Value: The value of the position of a digit in a number (e.g., in
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the number 321, the number 2 is in the “tens” position).
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(FrommOgdenmSJ,mFluhartymLK:mCalculationmofmdrugmdosages:mAmworkmtext,medm9,mSt
.mLouis,m2012,mElsevier/Mosby.)
, HESI Hint m
1 ten = 10 ones
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1 hundred = 100 ones
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1 thousand = 1000 ones
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Basic Addition m
Example 1 m
Steps
1. Line up the digits according to place value.
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2. Add the digits starting from right to left:
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• Ones: 2 + 3 = 5
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• Tens: 6 + 3 = 9
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• Hundreds: 4 + 1 = 5 m m m m m
Addition with Regrouping m m
, HESI Hint m
To solve an addition problem, it may be necessary to regroup by moving, or car
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Example 2 m
Steps
1. Line up the digits according to place value.
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2. Add:
• Ones: 5 + 9 = 14
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• Carry the 1 to the tens place, which is one place to the left.
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• Tens: 1 + 3 + 5 = 9
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• Hundreds: 8 + 5 = 13 m m m m m
Basic Subtraction
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Subtraction provides the difference between two numbers.
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, HESI Hint m
It may be easier to solve a subtraction problem by first rewriting it vertically.
m m m m m m m m m m m m m
Example 1 m
Steps
1. Line up the digits according to place value.
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2. Subtract:
• Ones: 4 − 2 = 2
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• Tens: 3 − 1 = 2
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• Hundreds: 2 − 1 = 1 m m m m m
• Thousands: 5 − 4 = 1 m m m m m
Subtraction with Regrouping m m
HESI Hint m
Remember, if the number to subtract is not a positive number, you must borrow
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Example 2 m