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Medical Math Lesson

    Adding and
Subtracting Decimals
       September - 2012
Essential Question:
• How do I add and subtract decimals?

It is very important that you:
1.Always line up decimals
2.Add and subtract like you always do
3.Bring decimal straight down in your
  answers
Adding
Examples:
               4.55 + 11.3
            Put the first number on
             the top of the second
            number and line up the   You can
                   decimals.        add a zero
                                      to help
                                       keep
                        4.55        everything
                                     lined up
                 + 11.3 0                         When adding
                                                 or subtracting
                    1 5. 8 5                       you always
                                                 start from the
                                                 right and work
                                                       left.
6.44 + 16

                  When there is
                  not a decimal
                     put one
                   behind the
     6+6=12         number.
   Write down
    the 2 and                     Add a zero
   carry the 1.                    to line up
Line up                           everything
                      1 6.44
  the
decimal            + 16. 0 0
                     22 . 4 4
8.33 + 10.972
                                       Annex (add) a
                           1 1        zero which acts
                                         as a decimal
                           8.330      place holder and
Set up vertically and
                                       helps lining up
       line up          + 10.972        the numbers.
    the decimals

                         1 9 .3 0 2
                                         Adding a zero is
                                            also called
                                        annexing a zero.
                                        It doesn’t change
                                         the value of the
                                             number.
Subtracting
Examples:
               5.34 -2.08
            Put the larger number on
              the top of the smaller
             number and line up the
                                       Don’t forget you may
                    decimals.            Need to borrow
                                           from the left
                                            to get the
                        2                    job done’
                        /4
                     5.3 1
                    -2.0 8
                               14-8=6
                      3. 2 6
                               2-0=2
                               5-2=3
28 – 15.911   Stack them
                               and line up
                                   the
                                 decimal
When there is                    points.
not a decimal,
 as in the 28,                       Add zeros to
   put one                              line up
  behind the        7 99             everything,
   number.                                then
                   28.0001
                                       subtract

                  -15.911
                   1 2.08 9
                               Start borrowing
                                from the left.
                                Start with the
                                 first number
                               smaller than the
                               number under it.
Magic Square

                   0.5    7

                  4.625

                  8.75


The sum of each               6.375     0.5     7
 row, column,
  and diagonal                5.25     4.625    4
  must be the
                              2.25      8.75   2.875
     same.
                                     Sums to
                                     13.875
Assignment: Problems 1-16 to be completed
without a calculator. Remember to show your
work for any credit. Turn into your instructor.

Edmodo quiz on addition and subtraction of
decimal values.

Decimals Add and Subtract

  • 1.
    Medical Math Lesson Adding and Subtracting Decimals September - 2012
  • 2.
    Essential Question: • Howdo I add and subtract decimals? It is very important that you: 1.Always line up decimals 2.Add and subtract like you always do 3.Bring decimal straight down in your answers
  • 3.
    Adding Examples: 4.55 + 11.3 Put the first number on the top of the second number and line up the You can decimals. add a zero to help keep 4.55 everything lined up + 11.3 0 When adding or subtracting 1 5. 8 5 you always start from the right and work left.
  • 4.
    6.44 + 16 When there is not a decimal put one behind the 6+6=12 number. Write down the 2 and Add a zero carry the 1. to line up Line up everything 1 6.44 the decimal + 16. 0 0 22 . 4 4
  • 5.
    8.33 + 10.972 Annex (add) a 1 1 zero which acts as a decimal 8.330 place holder and Set up vertically and helps lining up line up + 10.972 the numbers. the decimals 1 9 .3 0 2 Adding a zero is also called annexing a zero. It doesn’t change the value of the number.
  • 6.
    Subtracting Examples: 5.34 -2.08 Put the larger number on the top of the smaller number and line up the Don’t forget you may decimals. Need to borrow from the left to get the 2 job done’ /4 5.3 1 -2.0 8 14-8=6 3. 2 6 2-0=2 5-2=3
  • 7.
    28 – 15.911 Stack them and line up the decimal When there is points. not a decimal, as in the 28, Add zeros to put one line up behind the 7 99 everything, number. then 28.0001 subtract -15.911 1 2.08 9 Start borrowing from the left. Start with the first number smaller than the number under it.
  • 8.
    Magic Square 0.5 7 4.625 8.75 The sum of each 6.375 0.5 7 row, column, and diagonal 5.25 4.625 4 must be the 2.25 8.75 2.875 same. Sums to 13.875
  • 9.
    Assignment: Problems 1-16to be completed without a calculator. Remember to show your work for any credit. Turn into your instructor. Edmodo quiz on addition and subtraction of decimal values.