Step-by-step explanation:
The circumference of a circle is given by :
C=2πr, r is the radius of the circle
Also, 2r = D, diameter of the circle
⇒ C = πD
If the diameter of a circle is multiplied by 10, it means,
C = π(10)
⇒ C = 10π
Hence, if the diameter of a circle is multiplied by 10, then its circumference becomes 10π.