general Maths Puzzle

What is the remainder left after dividing 1! + 2! + 3! + ? + 100! By 7?
Think carefully !!!

Read Solution (Total 1)

All terms from 7!, i.e., 7!+8!+... are divisible by 7. So, remainder left after dividing 1! + 2! + 3! + ? + 100! By 7 is same as remainder left after dividing 1! + 2! + 3! + ? + 6! By 7.
1!+2!+3!+4!+5!+6! = 873
873 MOD 7 = 5
15 years agoHelpfull: Yes(6) No(0)

general Other Question

There is a shortage of tubelights, bulbs and fans in a village - Kharghar. It is found that
* All houses do not have either tubelight or bulb or fan.
* exactly 19% of houses do not have just one of these.
* atleast 67% of houses do not have tubelights.
* atleast 83% of houses do not have bulbs.
* atleast 73% of houses do not have fans.

What percentage of houses do not have tubelight, bulb and fan? One side of the bottom layer of a triangular pyramid has 12 balls. How many are there in the whole pyramid?
Note that the pyramid is equilateral and solid.