Convert the following binary numbers to octal

(a) 111010

(b) 110110101

(c) 1101100001

(a) 111010

Grouping in bits of 3:

$\underlinesegment{111} \quad \underlinesegment{010}$

Therefore, (111010)₂ = (72)₈

(b) 110110101

Grouping in bits of 3:

$\underlinesegment{110} \quad \underlinesegment{110} \quad \underlinesegment{101}$

Therefore, (110110101)₂ = (665)₈

(c) 1101100001

Grouping in bits of 3:

$\underlinesegment{001} \quad \underlinesegment{101} \quad \underlinesegment{100} \quad \underlinesegment{001}$

Therefore, (1101100001)₂ = (1541)₈