[HELP]

1) In a lab there are 10000 bulbs numbered from 10001 to 20000. The switches of these bulbs are also numbered in similar fashion.The switches are toggle switches i.e. pressing them once turns the corresponding bulb on and pressing the switch next time turns it off.(like the power button of ur TV remote).The lab attendant has a peculiar habit. One fine day he turns on all the bulbs. The next hour he presses the switches(i.e. he toggles them) that are multiples of 2. The following hour he toggles the switches which are multiples of 3. The following hour mulitples of 4 and then 5, 6 and so on till 20000. What bulbs remain glowing at the end?

2)A man buys 20 toys for rs 148. The toys are either red or white in colour.Each red toy costs Rs.8 and white toys cost Rs6.What wil be the cost of another set of 20 toys in which the present number of red and white toys are reversed ?