The numbers in a 'V' shape are 4, 5, and 2. The number at the bottom is 10. What is the rule connecting them?

• Left arm of 'V': 4
• Right arm of 'V': 5
• Point of 'V': 2
• Bottom number: 10

Let's try multiplying the numbers at the top of the 'V' arms and then dividing by the number at the point of the 'V'.

First, multiply the numbers at the top of the 'V' arms:

Next, divide this product by the number at the point of the 'V':

This result matches the given bottom number, 10.

The rule they used is: (Left arm number $\times$ Right arm number) $\div$ Point of V number = Bottom number.