How many grams are in 40 hectograms?

There are 400 grams in 40 hectograms. =)
You could also use the memory term KHDMDCM to help you next time ;-) 
I hope I helped! =D

Something i use to convert metric units is: King Henry Died By Drinking Chocolate Milk. This is an acronym for:
K: Kilos
H: Hecto
D: Deka
B: Base (liters or grams etc.)
D: Deci
C: Centi
M: Milli

Now, since you are going from hectograms (hecto) to grams (base) you will move the decimal to the right 2 times (since base is 2 bellow hecto) So that means: There are 4,000 grams in 40 hectograms.