What will be indexing to cut 30 teeth on a gear using simple indexing method?

Crank movement = 40/N
= ⁴⁰⁄₃₀
=1 ¹⁰⁄₃₀
=1 ¹⁄₃
Case 1: Multiplying both numerator and denominator by 5
We will get,
Crank movement = 1 ⁵⁄₁₅
Denominator becomes ?15?, therefore select 15 hole circle plate.
This means that after each operation rotates indexing crank by one complete turn and 5 holes in 15 holes circle.
Case 2: Multiplying both numerator and denominator by 7
We will get,
Crank movement = 1 ⁷⁄₂₁
Denominator becomes ?21?, therefore select 21 hole circle plate.
This means that after each operation rotates indexing crank by one complete turn and 7 holes in 21 holes circle.
Similarly, we can multiply and divide by other numbers too, provided that the index plate with required holes is available.