20 metres in 1 minute = 20*60 metres in one hour = 20*60*24 metres in one day = 20*60*24*365 metres in one year = 20*60*24*365*100 metres in one century = 20*60*24*365*100*100 centimetres in one century
$${\mathtt{20}}{\mathtt{\,\times\,}}{\mathtt{60}}{\mathtt{\,\times\,}}{\mathtt{24}}{\mathtt{\,\times\,}}{\mathtt{365}}{\mathtt{\,\times\,}}{\mathtt{100}}{\mathtt{\,\times\,}}{\mathtt{100}} = {\mathtt{105\,120\,000\,000}}$$
.