Exponents

102 = 10 x 10 = 100

103 = 10 x 10 x 10 = 1,000

104 = 10 x 10 x 10 x 10 = 10,000

also 101 = 10

and 100 = 1
Look at these examples. The first says 10 to the second power, or 10 squared, is 10 times 10 or 100. Then 10 cubed is 10 times 10 times 10 or 1,000.   Next, 10 to the fourth is 10 times 10 times 10 times 10 or 10,000. Also, 10 to the first power is simply 10. Less obviously, 10 to the zero power equals one. Note that 10 to any positive power is just one followed by that number of zeros.
10-1 =  1 =  0.1
       10

10-2 =  1  =    1   =   1  = 0.01
       102    10x10    100

10-3 =  1  =    1    =   1   =  0.001
       103   10x10x10  1,000

10-4 =  1  =     1     =   1   = 0.0001
       104  10x10x10x10  10,000
These examples deal with negative exponents. A negative sign in the exponent means the inverse or reciprocal of the same number without a negative sign. Ten to the minus one means one over ten (one over ten to the first power) which is point one (one tenth). Ten to the minus two means one over ten squared or point zero one (one hundredth). Ten to the minus three means one thousandth, and so forth. When negative exponents are used as powers of ten, the exponent indicates the number of places following the decimal point up to and including the one.
104    = 10,000

103     =   1,000

102    =      100

101    =        10

100    =           1

10-1   =          0.1

10-2   =           0.01

10-3   =           0.001

10-4   =           0.0001
This table summarizes the powers of 10 and shows what they represent in regular decimal numbers, from 10 to the fourth being the same as 10,000 down to 10 to the minus fourth meaning 1/10,000 or .0001.