16
Number Notations, Arithmetical Operations, and Calculators
lent information. Although you will normally use your calculator to deal with
logs, you should be able to handle log problems with simple log tables when
your calculator is broken down or not available.
ANTILOGARITHMS
The number that corresponds to a given logarithm is known as the antilogarithm, or antilog. Like logs, the antilogs are more easily obtained from a
calculator than from a log table, but you should be able to use both methods.
With a calculator you would find the antilog as follows.
1. Enter the given log through the keyboard. Use the "change sign" key
after entry if the log is negative, don't use the — key (i e , the subtract
key).
2. Press the antilog key (or keys). On an HP-type calculator a common
key symbol is 10*; on a Tl-type calculator you would usually press the
INV and LOG keys, in that order.
3. The antilog appears in the lighted display.
Check your ability to find antilogs with your calculator, knowing that antilog
0.77815 = 6.00000, antilog 5.39756 = 2.49781 x 10
5
, and antilog (-3.84615) =
1.42512 x 10~
4
.
With a log table you would find the antilog as illustrated by the following
problems.
PROBLEM:
Find the antilog of 4 5502
SOLUTION:
We want the number that corresponds to 10"
5502 = 10°
5502 x 10
4 Locate the
mantissa, which is 0 5502, in a log table, then find the value of N that has this log
The mantissa 0 5502 lies in the row corresponding to 3 5 and in the column headed
by 5 Therefore the number corresponding to 10°
5502 is 3 55, and the number we
seek is 3 55 x 10"
PROBLEM:
Find the antilog of -6 7345
SOLUTION:
We want the number that corresponds to 10~
6 7345 = 10°
2655 x 10~
7 Note that we
must have a positive exponent for the lefthand factor, the sum of the two exponents is still -6 7345 Locate the mantissa, which is 0 2655, in the log table, then
Number Notations, Arithmetical Operations, and Calculators
lent information. Although you will normally use your calculator to deal with
logs, you should be able to handle log problems with simple log tables when
your calculator is broken down or not available.
ANTILOGARITHMS
The number that corresponds to a given logarithm is known as the antilogarithm, or antilog. Like logs, the antilogs are more easily obtained from a
calculator than from a log table, but you should be able to use both methods.
With a calculator you would find the antilog as follows.
1. Enter the given log through the keyboard. Use the "change sign" key
after entry if the log is negative, don't use the — key (i e , the subtract
key).
2. Press the antilog key (or keys). On an HP-type calculator a common
key symbol is 10*; on a Tl-type calculator you would usually press the
INV and LOG keys, in that order.
3. The antilog appears in the lighted display.
Check your ability to find antilogs with your calculator, knowing that antilog
0.77815 = 6.00000, antilog 5.39756 = 2.49781 x 10
5
, and antilog (-3.84615) =
1.42512 x 10~
4
.
With a log table you would find the antilog as illustrated by the following
problems.
PROBLEM:
Find the antilog of 4 5502
SOLUTION:
We want the number that corresponds to 10"
5502 = 10°
5502 x 10
4 Locate the
mantissa, which is 0 5502, in a log table, then find the value of N that has this log
The mantissa 0 5502 lies in the row corresponding to 3 5 and in the column headed
by 5 Therefore the number corresponding to 10°
5502 is 3 55, and the number we
seek is 3 55 x 10"
PROBLEM:
Find the antilog of -6 7345
SOLUTION:
We want the number that corresponds to 10~
6 7345 = 10°
2655 x 10~
7 Note that we
must have a positive exponent for the lefthand factor, the sum of the two exponents is still -6 7345 Locate the mantissa, which is 0 2655, in the log table, then