ok, it's been longer than I thought... I dug out an old program, and you don't put anything:
PRINT "NUMBER OF PAYMENTS IN THE FIRST YEAR <" FIRST "> ";
INPUT A
IF A < > 0 THEN FIRST = A
this is from a mortgage program I wrote, where FIRST is a variable for how many payments were payed on the loan in the first year... if you rerun it, it keeps and prints the default value for FIRST, and if you hit enter, it stays, or if you enter a number, it replace the FIRST variable with what you entered.