Given a simple high-school level math question, you are required to solve it and provide the final answer. The final answer is always a single number. These questions can range from a variety of topics like simple arithmetic, solving equations, converting a quantity from one unit to another, finding remainders/GCD/LCM, finding probabilities etc. Each question has only one correct answer. This answer can be a positive or negative integer, a fraction or a decimal number. If the answer is a negative number use the hyphen (e.g. -42) symbol for the minus sign. For decimal numbers, do not add extra zeros after the decimal point. For fractional numbers, separate the numerator and denominator using a forward slash (e.g. 3/25).

[EX Q]: Convert 6.264243mg to tonnes.
[EX A]: 0.000000006264243

[EX Q]: Calculate prob of sequence dqd when three letters picked without replacement from fqfuurdttdft.
[EX A]: 1/660

[EX Q]: Two letters picked without replacement from {n: 10, t: 2}. Give prob of sequence tt.
[EX A]:
1/66