If the secondary consumers is one of the food chains used 4200 kcal, what amount of energy was absorbed by the producers?

I think it's 420,000 kcal, because 10% of energy is lost as you move up each trophic level. To find what you started with you would multiply by 10 instead of dividing by 10. You have to multiply by 10 twice, because of the primary consumers and producers.