Previous in Permutation and Combination Next in Permutation and Combination
Question Number 130602 by EDWIN88 last updated on 27/Jan/21
Answered by mr W last updated on 27/Jan/21
$$={number}\:{of}\:\mathrm{4}\:{digit}\:{numbers}\:{which} \\ $$$${are}\:{divisible}\:{by}\:\mathrm{3}: \\ $$$$\mathrm{1002},\:\mathrm{1005},\:...,\:\mathrm{9999} \\ $$$$\Rightarrow\frac{\mathrm{9999}−\mathrm{1002}}{\mathrm{3}}+\mathrm{1}=\mathrm{3000} \\ $$$${i}.{e}.\:{there}\:{are}\:\mathrm{3000}\:{five}\:{digit}\:{numbers} \\ $$$${ending}\:{with}\:\mathrm{6}\:{and}\:{divisible}\:{by}\:\mathrm{3}. \\ $$