Download Basic Math Rules Review

Basic Math Rules Review
ADDITION AND SUBTRACTION OF DECIMALS
Rule: When adding or subtracting decimals, place the numbers in a column with the decimal point aligned
Solution:
MULTIPLICATION AND DIVISION OF DECIMALS
Rule:
When multiplying decimal numbers the product contains as many decimal places as the sun
1.256
0.12
+12.3
1.256
0.120
+12.300
13.676
13.676
Zeros may be added
behind the last digit
if desired
of the decimal laces in the numbers being multiplied.
Example: P:ult?ply 22.3 y 4.12
solution: The number
22.3
X 4.12
446
Put the decimal three
223
places to the left to
892
91876
give: 91.876
Answer: 22.3 X,4.12 = 91.876
Solution:
Example: Divide 3.5 divided 2.5 = 2.5/3.5 =
1.4
When the divisor is a
35. 0/25
decimal number it
35-25=10
must be converted to
10 add 0= 100
a whole number by
100-100=0
moving the decimal
Answer:
2.5/3.5 = 1.4
Rule:
To change a fraction to a decimal, the numerator is divided by the denominator.
Simplifying Complex Fractions
In complex fractions, the numerator, the denominator, or both contain a fraction. The complex fraction is converted
into a simple fraction, and mixed number, a decimal number, or a whole number when it is simplified.
Rule:
To simplify a complex fraction, invert the denominator and multiply the numerator by the
denominator.
The steps used to simply the complex fraction are illustrated below:
A.
B.
1 tab
1gr is the same as 1 tab x 1gr
3
3
1 tab x 3 is What you get if you invert then multiply
1gr
1 tab
C.
C.
1 tab
3 replaces 1gr
lgr
3
X
Therefore:
Substitute the simplified fo: m of the expression into the equation in place of the complex function.
Substitute the simplified form of the expression into the equation in place of the complex function
ROUNDING NUMBERS
If the last digit in a number is 5, 6, 7, 8, or 9 increase the digit in front of it by one. If the last digit is 1, 2, 3, 4, then drop
the last digit. With decimal numbers it is often necessary to round to the nearest tenth, hundredth, or thousandth. If the
answer is to be left in tenths you must work the problem out to hundredths then round back. If the answer is to be left
in whole numbers then you must work the problem to tenths then round back. In this unit work all problems with an
answer less than one (I) to three decimal places but leave the answer in two decimal places. If the answer is more than
one, work the problem out to two decimal places and leave the answer in one decimal.