Math Riddles

Question: When i was 4 my sister was half my age. Now I am 100. How old is my sister now?

Question: How much does the brick weigh if a brick weighs 1kg plus a half brick?

Question: this is a 6 digit number. this number has two decimal places. there are no tenths or tens in this number. the tenths digit plus the hundredth digit equals 6. if you divide the thousands digit by 2 the answer is 2. the hundreds digit is the same as today's date. the units digit is half the hundredths unit.

Question: A man lives in an apartment building on the 100th floor. He rides the elevator all the way down to floor 1 every morning then all the way up to floor 100 every evening. The elevator is coin-operated. It costs $0.25 per floor for floors 1-25, $0.50 per floor for floors 26-50, $0.75 per floor for floors 51-75, and $1.00 per floor for floors 75-100. How much money does the man spend each day riding the elevator?

Question: How do you make 9 by just 3 toothpicks?