find the cardinal number for the following sets, A={108,109,110,111,...153}

Question

find the cardinal number for the following sets, A={108,109,110,111,...153}

B={108,110,112,...208}

 

Answer 1

{108, 109, 110, 111, ..., 153}

if you had {1, 2, 3, 4, ..., 153} you would have 153 numbers but you are missing 1, 2, 3, ..., 107

you are missing 107 numbers

153-107=46 numbers

or, 153-108=45, 45+1=46

 

{108, 110, 112, ..., 208}

if you had {2, 4, 6, 8, ..., 208} you would have 104 even numbers and the 104 odd numbers would be left out

you are missing 2, 4, 6, 8, ..., 106

if you had 1, 2, 3, 4,..., 106 you would have 106 numbers but you only have even numbers so you have 53 numbers missing

104-53=51 numbers

 

or 208-108=100, 100/2=50, 50+1=51