I want to know how many possible combinations are there for the colors of the rainbow (7) colors for two colors like blue and green then bluer and red then blue and yellow liked that ok bye

Question

I want to know how many possible combinations there Are for dying my hair every color of the rainbow until running out of ideas it's not for me it's bc this band member from 5sos Dyes his hair like every week a different color so I wanna know how many till he runs out of combinations  ok bye

Answer 1

The answer is how many combinations of two colours can you make from 7 different colours.

Combinations=7*6/2=21. That's 21 weeks.

REASONING: Choice for 1st colour: 7 leaving 6 colours. Choice for 2nd colour: 6. Combine the two=7*6=42. But the colours can be in either order so 42/2=21.