Question Number 211147 by hardmath last updated on 29/Aug/24
$$ \\ $$1414; 1515; 1616;…; From 5757 units
How many of them are divided by 13 and the remainder is 10?
Answered by mm1342 last updated on 30/Aug/24
$$−{a}−\mathrm{4}{b}−\mathrm{3}{c}+{d}\overset{\mathrm{13}} {\equiv}\mathrm{10} \\ $$$$\Rightarrow{a}+\mathrm{4}{b}+\mathrm{3}{c}−{d}\overset{\mathrm{13}} {\equiv}\mathrm{3} \\ $$$${for}\:\:“\:{abab}\:''\:{if}\:\:{abab}\overset{\mathrm{13}} {\equiv}\mathrm{10}\Rightarrow\:\mathrm{4}{a}+\mathrm{3}{b}\overset{\mathrm{13}} {\equiv}\mathrm{3}\:\:;\:\mathrm{1}\leqslant{a}\leqslant\mathrm{5} \\ $$$$\Rightarrow\mathrm{4}{a}+\mathrm{3}{b}=\mathrm{3}\:{or}\:\mathrm{16}\:{or}\:\mathrm{29}\:{or}\:\mathrm{42}\:\:… \\ $$$${a}=\mathrm{1}\Rightarrow\mathrm{3}{b}=\mathrm{12}\Rightarrow{b}=\mathrm{4}\Rightarrow\mathrm{1414}\:\checkmark \\ $$$${a}=\mathrm{2}\Rightarrow\mathrm{3}{b}=\mathrm{21}\Rightarrow{b}=\mathrm{7}\Rightarrow\mathrm{2727}\:\:\checkmark \\ $$$${a}=\mathrm{4}\Rightarrow\mathrm{3}{b}=\mathrm{0}\Rightarrow{b}=\mathrm{0}\Rightarrow\mathrm{4040}\:\:\:\checkmark \\ $$$${a}=\mathrm{5}\Rightarrow\mathrm{3}{b}=\mathrm{9}\Rightarrow{b}=\mathrm{3}\Rightarrow\mathrm{5353}\:\:\:\checkmark \\ $$$$ \\ $$
Commented by hardmath last updated on 30/Aug/24
$$\mathrm{dear}\:\mathrm{professor}\:\mathrm{2127}.? \\ $$
Commented by hardmath last updated on 30/Aug/24
$$ \\ $$the answer is 4, but 2127 does not pay
Commented by Rasheed.Sindhi last updated on 30/Aug/24
$$\mathcal{T}{ypo}!\:{It}'{s}\:\mathrm{2727}\:{instead}\:{of}\:\:\:\mathrm{2127} \\ $$
Commented by mm1342 last updated on 30/Aug/24
$$\:\underline{\underbrace{\lesseqgtr}} \\ $$