This once got a different system then my other one on here.
That lower 555 delivers currency for a certain adjustable amount of time...
During 10 seconds for instance the rest of the counter circuit will work and measure the revolutions within. The revolutions are simulated by the upper 555.
To add more displays just copy the first stage.
Enjoy
βοΈπππΊπ·ππΈπ¦πΊπ¬π§π©πͺπ³πΏππ½πππβ¨π°πβ¨πππ«πΊππΊπΈπ¬π§πΉ