Since CALCULUS has 8 letters with 2 indistinguishable C's, 2 indisnguishable L's and 2 indistinguishable U's, the answer is= 5040.
Example: UALCLSCU Choose the letter to begin and end with in 3 ways, C,L, or U. In the example we just need the distinguishable arrangements of ALCLSC which is= 180 Answer: 3*180 = 540. Edwin