Ten
This cross is the symbol for the number ten. A good way to remember this is to think about all the religions that have crosses and also important sets of tens.
If you're familiar with Christianity, they have a cross and ten commandments. Cross = ten, you see?
じゅう
とお
None
This cross in particular has ten jewels (じゅう) on it. Two on each arm and two in the middle. That's ten jewels!
Picture the jewels on this cross. Maybe draw it out on a piece of paper so the visual really sticks. Each cross is really a symbol for different sets of ten things, and in this case, it's ten jewels.