## Search found 1175 matches

- Sun Jan 30, 2011 9:26 am
- Forum: Secondary: Solved
- Topic: Dhaka Secondary 2011/7
- Replies:
**11** - Views:
**9062**

### Re: Dhaka Secondary 2011/7

I don't think so!

- Sat Jan 29, 2011 11:01 pm
- Forum: Secondary: Solved
- Topic: Dhaka Secondary 2011/9
- Replies:
**9** - Views:
**7703**

### Re: Dhaka Secondary 2011/9

This one is really tricky,here is how I tamed it- Solution: We know that $2\equiv -1(mod 3) \Rightarrow2^x\equiv (-1)^x(mod 3)$ So we can strike out the numbers divisible by $3$. Now again the numbers which 'survive' are always like this- $x^2\equiv 1 (mod 3)$ So we have to just sum up the first $20...

- Sat Jan 29, 2011 10:49 pm
- Forum: Secondary: Solved
- Topic: Dhaka Secondary 2011/7
- Replies:
**11** - Views:
**9062**

### Re: Dhaka Secondary 2011/7

Solution:

- Sat Jan 29, 2011 10:43 pm
- Forum: Secondary: Solved
- Topic: Dhaka Secondary 2011/4
- Replies:
**2** - Views:
**2088**

- Sat Jan 29, 2011 10:32 pm
- Forum: Secondary: Solved
- Topic: Dhaka Secondary 2011/1 (Higher Secondary 2011/1)
- Replies:
**9** - Views:
**8102**

### Re: Dhaka Secondary 2011/1 (Higher Secondary 2011/1)

The answer isn't the one Tahmid posted,it is as follows- The answer is 76. Here we must know that in the silver ring set,there are 12 kinds,and in the gold ring set,there are 10 kinds.So at least 2 kinds of silver ring is different from the gold kinds.Now if we pick up 75 rings , all of them can be ...