$$\color{green}{\text{Happy New Year!!!}}$$

Question

anonymous · Answer

1. 2013 is the ﬁrst year since the Middle Ages that consists of four consecutive digits. How many
such years are there still to come after 2013 (and before the year 10000)?

kc_kennylau · Answer

Years with consecutive digits: (order temporarily not counted)
3210
4321
5432
6543
7654
8765
9876

kc_kennylau · Answer

Years already passed:
0XXX (6 years)
1XXX (6 years)
2013 (1 year)

kc_kennylau · Answer

Therefore the answer is:
$$7\times4!-13$$$$=7\times24-13$$$$=155$$

anonymous · Answer

wow short n succint ...very clear solution,this is the best response!!!

kc_kennylau · Answer

thanks :) may I ask what "succint" means?

anonymous · Answer

he meant succinct lol

def: briefly and clearly expressed.

kc_kennylau · Answer

Thank you, English is not my native language

anonymous · Answer

lol see how much you learn at OS,Manglish!!haha

kc_kennylau · Answer

I'm not from Malaysia... ??

anonymous · Answer

loooooool haha @Euler271 come help

kc_kennylau · Answer

Please don't use slangs, I'll just google them and take the wrong meaning :)

anonymous · Answer

lol i used the two words mathematics+english=manglish

kc_kennylau · Answer

lolz i searched it in google and got what you'd get