print "2^64"
a$ = "1"
for i = 1 to 64
	a$ = multByD$(a$, 2)
next
print a$
print "(check with native BASIC-256)"
print 2^64
print "(looks OK)"

#now let's do b$*a$ stuff
print
print "2^64*2^64"
print longMult$(a$, a$)
print "(check with native BASIC-256)"
print 2^64*2^64
print "(looks OK)"
end

function max(a, b)
	if a > b then
		return a
	else
		return b
	end if
end function

function longMult$(a$, b$)
	signA = 1
	if left(a$,1) = "-" then
		a$ = mid(a$,2,1)
		signA = -1
	end if
	signB = 1
	if left(b$,1) = "-" then
		b$ = mid(b$,2,1)
		signB = -1
	end if

	c$ = ""
	t$ = ""
	shift$ = ""
	for i = length(a$) to 1 step -1
		d = fromradix((mid(a$,i,1)),10)
		t$ = multByD$(b$, d)
		c$ = addLong$(c$, t$+shift$)
		shift$ += "0"
	next
	if signA * signB < 0 then c$ = "-" + c$
	return c$
end function

function multByD$(a$, d)
	#multiply a$ by digit d
	c$ = ""
	carry = 0
	for i = length(a$) to 1 step -1
		a = fromradix((mid(a$,i,1)),10)
		c = a * d + carry
		carry = int(c/10)
		c = c mod 10
		c$ = string(c) + c$
	next
	if carry > 0 then c$ = string(carry) + c$
	return c$
end function

function addLong$(a$, b$)
	#add a$ + b$, for now only positive
	l = max(length(a$), length(b$))
	a$ = pad$(a$,l)
	b$ = pad$(b$,l)
	c$ = "" #result
	carry = 0
	for i = l to 1 step -1
		a = fromradix((mid(a$,i,1)),10)
		b = fromradix((mid(b$,i,1)),10)
		c = a + b + carry
		carry = int(c/10)
		c = c mod 10
		c$ = string(c) + c$
	next
	if carry > 0 then c$ = string(carry) + c$
	return c$
end function

function pad$(a$,n)  #pad$ from right with 0 to length n
	pad$ = a$
	while length(pad$) < n
		pad$ = "0" + pad$
	end while
end function