Nathanial Hendler wrote: > So then which value of j is used in the definition of l? > > l = i - j > > Any ideas? The last one. Solve the equations sequentially, or rename the variables and reassign the names. Try this in basic: INPUT "Given year: ", y c = CINT(y / 100) n = y - (19 * INT(y / 19)) k = INT((c - 17) / 25) i = c - INT(c / 4) - INT((c - k) / 3) + 19 * n + 15 i = i - 30 * INT(i / 30) i = i - INT(i / 28) * (1 - INT(i / 28) * INT(29 / (i + 1)) * INT((21 - n) / 11)) j = y + INT(y / 4) + i + 2 - c + INT(c / 4) j = j - 7 * INT(j / 7) l = i - j m = 3 + INT((l + 40) / 44) d = l + 28 - 31 * INT(m / 4) PRINT m PRINT d reassigned version ("c like"): y=2010 c=floor(y/100) n=y-19*floor(y/19) k=floor((c-17)/25) i=c-floor(c/4)-floor((c-k)/3)+19*n+15 z=i-30*floor(i/30) w=z-floor(z/28)*(1-floor(z/28)*floor(29/(z+1))*floor((21-n)/11)) j=y+floor(y/4)+w+2-c+floor(c/4) u=j-7*floor(j/7) l=w-u m=3+floor((l+40)/44) d=l+28-31*floor(m/4) floor means int, in "Derive" syntaxis. Dennis Crawley Argentina -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist