For the 8-bit word 00111001, the check bits stored with it would be 0111. Suppose when the word is read from memory, the check bits are calculated to be…

Explanation

Data bits: d₈ = 0, d₇ = 0, d₆ = 1, d₅ = 1, d₄ = 1, d₃ = 0, d₂ = 0, d₁ = 1. Stored check bits p₈p₄p₂p₁ = 0111. Codeword layout (positions 12 to 1): d₈ d₇ d₆ d₅ p₈ d₄ d₃ d₂ p₄ d₁ p₂ p₁. Syndrome = 0111 XOR 1101 = 1010 = 10, so bit position 10, which holds d₆, is in error. Flipping d₆ gives the word that was read: 00011001.