1. The problem is to evaluate the expression $20 + 2^3 \times 3 - 1$. 2. According to the order of operations (PEMDAS/BODMAS), we first evaluate exponents, then multiplication and division from left to right, and finally addition and subtraction from left to right. 3. Calculate the exponent: $2^3 = 8$. 4. Substitute back into the expression: $20 + 8 \times 3 - 1$. 5. Perform the multiplication: $8 \times 3 = 24$. 6. Substitute back: $20 + 24 - 1$. 7. Perform the addition: $20 + 24 = 44$. 8. Perform the subtraction: $44 - 1 = 43$. 9. Therefore, the value of the expression is $43$.