Exams

International Day for Disaster Reduction, held every 13 October, celebrates how people and communities around the world are reducing their exposure to disasters.

The year 2017 focus is : Reducing the number of affected people by disasters by 2030.

Turkmenistan, is the Asian country which has recently launched its 1st messaging app BizBarde.

Egypt is called as the gift of the Nile river. It is called so because the nile river served as means for transport, help in irrigation for farming, made soil fertile for growing crops. It made the Egyptian civilization possible. 

Satellites orbit the earth at a speed of 28,000 kmph.

Satellites that are further away actually travel slower. The International Space Station has a Low Earth Orbit, about 400 kilometers (250 miles) above the earth's surface. Objects orbiting at that altitude travel about 28,000 kilometers per hour (17,500 miles per hour).

Nine in total. 6 daughters and a brother in common, 2 parents.

We know that zero can't be in hundreds place. But let's assume that our number could start with zero.

The formula to find sum of all numbers in a permutation is

111 x no of ways numbers can be formed for a number at given position x sum of all given digits

No of 1 s depends on number of digits

So,the answer us

111 x 20 x (0+1+2+3+4+5) = 33300

We got 20 as follows. If we have 0 in units place we can form a number in 4*5 ways. This is for all numbers. So we have substituted 20 in formula.

Now, this is not the final answer because we have included 0 in hundreds place. so we have to remove the sum of all numbers that starts with 0.

This is nothing but the sum of all 2 digits numbers formed by 1 2 3 4 5. Because 0 at first place makes it a 2 digit number.

So the sum for this is 11 x 4 x (1+2+3+4+5).
=660

Hope u understood why we use 4. Each number can be formed in 4x1 ways

So, the final answer is 33300-660 = 32640