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).

Q: How many nanometers are there in 21/2 of a micrometer?

A: 10500
****
Q: Three letters picked without replacement from {j: 2, y: 2, k: 1, u: 4}. Give prob of picking 2 j and 1 u.

A: 1/21
****
Q: Calculate prob of sequence sssh when four letters picked without replacement from hsss.

A:
1/4
****