Zero is an even number. A number is called “even” if it can be marked off in groups of 2 with none left over. For example, 4 is even with 2 pairs; 5 is odd with 2 pairs and 1 leftover. In a group of zero objects, there are no leftover objects, so zero is even. Now you know!

The rainbow at night is called a moonbow or lunar rainbow. It is produced by moonlight instead of sunlight. Other than the fact that it has a different light source, a moonbow is the same as a solar rainbow.

A common mistake is to divide 50 into half instead of 50 by half. It pays to read the question carefully!

When you mix the colours of lights (additive colour mixing), you’re mixing wavelengths. Combining all the different wavelengths of light will give you white light. Think of how shining a white light through a prism gets you a rainbow — it’s because all these colours make up white light.

When mixing paint, subtractive colour mixing happens, which is different from mixing light. Paint absorbs all light except the colour they emit (e.g. red paint absorbs all light except red). So, the more paints you mix, the more colours they absorb, resulting in a black or very dark brown colour.

It may seem unintuitive but the answer is 5 cents. Here’s the math: Let x=bat and y=ball (x + y) = 1.10, x = (1 + y), (1+y+y)=1.10, 2y = 0.1, y=0.05. Don’t be disheartened if you got this wrong. Psychologist and Nobel Prize-winner Daniel Kahneman suggests that we have a quick, intuitive mental system and a slow, rationale mental system. If you answered 10 cents, you’ve likely used your intuitive system to jump to the answer.

The density of water is 1g/cm^3. Assuming a cup of water is 236cm^3: Number of atoms in a cup = 236cm^3 x (1g/cm^3) x (1mol/18g) x (6.02x 10^23/mol) x 3 = 2.37 x 10^25 atoms. As for cups of water in all the oceans, it is estimated that there are 321 million cubic miles of water, or 1.34 x 102^4ml. Number of cups in all the world’s oceans =1.34 x 10^24 divide 236 =5.67 x 10^21. So, it seems like there’s almost 4,200 times more atoms in a cup compared to cups of water in all the world’s oceans!

In order to taste any food, chemicals from the food must dissolve in your saliva. Once they’re dissolved only then can they be detected by receptors on taste buds.

Based on the report by NASA, there are about 100 – 400 billion stars in the Milky Way. On the other hand, research published in the scientific journal Nature estimates the number of trees on Earth to be 3.04 trillion.

In its gaseous state, oxygen is colourless. However, when it is in the form of liquid and solid, oxygen is pale blue.

Due to the zero-gravity environment, astronauts can end up growing 3 inches (7.6cm) taller on the International Space Station. Unfortunately, their muscles will also get smaller and weaker since the body is no longer using the muscles to fight gravity, unlike on Earth.

The function g(f(x)) means to substitute f(x) into g(x). So if f(x) is pizza and g(x) is pineapple, it means to put pizza into pineapple. What about a Hawaiian pizza, i.e. pineapple in pizza? Well, that would be the function f(g(x))!