I am reading a book called advanced physics, which is very good I may add. there is a question in it as follows; The second is defined as 9,192,631,770 periods of radiation from a caesium-133 atom, The metere is defined as the distance travelled by light in 1/299792458 of a second. How many wavelengths of caesium-133 radiation used to define the second is this? So I started with 1/299792458 this equals 3.3x10^-9 then 9,192,631,770 / 3.3x10^-9 but obviously when dividing powers you minus them and a minus and minus make a plus this gives the answer 2.8x10^18. I must be doing something wrong as this is a higher answer than the initial amount of radiation in a second? This is not a homework question but not being able to work it out aggravates me!