Decades: 1200s 1210s 1220s 1230s 1240s - 1250s - 1260s 1270s 1280s 1290s 1300s
Years: 1245 1246 1247 1248 1249 - 1250 - 1251 1252 1253 1254 1255
Births
Deaths
... square[?]. To "complete the square" is to add a constant (i.e., in this case, a quantity that does not depend on x) to the expression to the left of "=", that will make it ...