[tex]Greatest\ common\ factor\ is\ the\ highest\ number\ by\ witch\ 480\ and\\ 1000 \ can\ be\ divided\\\\
480:2\\
240:2\\120:2\\60:2\\30:2\\15:3\\5:5\\\\
1000:2\\
500:2\\
250:2\\125:5\\25:5\\5:5\\\\GCF=2^3*5=8*5=40\\\\Greatest\ common\ factor\ of\ 480\ and\ 1000\ is\ equal\ to\ 40.
[/tex]