Binary numbers represented with 1 & 0 using base 2.
It means the last number is 2⁰

Remember powers of 2 by heart.

How you convert a binary number like 110111 to decimal
Easy!
1 x 2⁵ + 1 x 2⁴ + 0 x 2³ + 1 x 2² + 1 x 2¹ + 1 x 2⁰
32 + 16+ 0+ 4+2+ 1
55
is this answer is correct ?

Example II

Try binary numbers 1, 11, 111, 1111, 11111, 111111, 1111111 and 11111111
Try binary numbers 0, 10, 100, 1000, 10000, 100000
Try binary numbers 101, 1010, 101010

Remember these patterns by heart.