MACHINE SHOP CALCULATION - OD1640 - LESSON 2/TASK 3
column adds up to 60 or more, proceed similarly, remembering that seconds
change to minutes and minutes to degrees.
Take away 60" from 81" and
add 1' to 133'. Then take
away 120' from 134' and add
2,, to 58,,. After becoming
accustomed to this procedure,
the values can be carried to
their respective columns mentally.
To subtract angles, arrange the degrees, minutes, and seconds in
separate columns, with the larger angle on top.
Then subtract the
individual columns. If the upper number in a column is too small to allow
subtraction, one unit must be taken away from the following column and 60
units added to the insufficient number.
This makes the subtraction
Subtract 14,, 51' 30" from 86,, 45' 10".
Here the subtraction cannot be
performed in either the seconds
or the minutes columns.
Hence take away 1' from 45'
leaving 44', and add 60" to 10",
getting 70". Also, take 1,,
from 86,,, leaving 85,,, and add
60' to 44', getting 104'.
To multiply an angle by a number, it is necessary to multiply each
column by the given number. Then, if the answers in the "seconds" or the
"minutes" columns are greater then 60, they must be reduced, as in the
addition of angles.