Periods on the periodic table represent

all that

- with the same number of valence electrons
- with increasing number of valence electrons
- with the same number of electron orbits
- with increasing atomic size

- decrease the number of plants and animals living in the water.

the answer is 1260

you spend 7 hours in school for 1 school day with 5 school days in 1 school week with 36 school weeks in a school year.

7*5*36= 1260 it's all about multiplying