243 has a decent number of factors (1, 3, 9, 27, 81, 243), so you have a few choices. The most obvious one is simply 243 * 1 = 243. 3 * 81 and 9 * 27 also work.
313
-19
23
8.31 comes closest.
6x5 2x15 1x30
81 x 3 = 243
1 and 243.
1 x 243, 3 x 81, 9 x 27
A number multiplied by itself added to itself equals 30. What are the two possible numbers?
15x60
The numbers are: -25 and -30
313
41x2=82
421 and 23
-19
23
81.9 and 10 are two numbers which, when multiplied together, make 819.