Do you mean significant digits?

When dividing/multiplying express the answer with the number of sig digs the LEAST accurate number in the question had.

So 21.3/1.3 = 16 (the least sig was 1.3 with 2 sig digs so the answer is in 2 sig digs).

To express that in one sig dig it would be 20, which is horribly inaccurate.