Question

The duplex of 5 is options a.10 b.25 c.5 d.20

Answer 1

The duplex of number 5 is 25.

• The duplex of a number is altogether the square of the number for a single-digit number.  
• Whereas, the duplex of a number represents typically twice the sum of the two digits of the integer, for a two-digit integer.

• For example - 2² = 4

        5² = 25

        8² = 64

        48 = 2 × 4 × 8 = 64

        81 = 2 × 8 × 1 = 16