If values of P=3, R=27, T=243, then find the value of Q+S = ________ .

Key insight: each letter's value is a power of 3 where the exponent equals the letter's alphabet position minus 15.

• Verify the pattern using the given values: P is the 16th letter, so value = 3^(16−15) = 3^1 = 3; R is the 18th letter, so value = 3^(18−15) = 3^3 = 27; T is the 20th letter, so value = 3^(20−15) = 3^5 = 243.

• Compute Q and S using the same rule: Q is the 17th letter → Q = 3^(17−15) = 3^2 = 9; S is the 19th letter → S = 3^(19−15) = 3^4 = 81.

• Add the values: Q + S = 9 + 81 = 90.