Binary multiplication has 4 basic rules:

• 0 × 0 = 0
• 0 × 1 = 0
• 1 × 0 = 0
• 1 × 1 = 1

To multiply binary numbers, follow these steps:

1. Set the longer number as the multiplier and the shorter number as the multiplicand.
2. Multiply the multiplier by each digit of the multiplicand to achieve intermediate products, whose last digit is in the position of the corresponding multiplicand digit.
3. Sum the intermediate products to get the final product.

To multiply the binary numbers 101 and 11, follow these steps:

1. Set 101 as the multiplier and 11 as the multiplicand.
2. Multiply 101 with the last digit of 11: 101 × 1 = 101. This is the first intermediate product.
3. Multiply 101 with the first digit of 11: 101 × 1 = 101. Add a 0 in the end to represent the multiplicand's digit position: 1010. This is the second intermediate product.
4. Sum the intermediate products to get the final product: 101 + 1010 = 1111.